🌏 中文版
You're rappelling, your brake hand slips, and the rope starts running through the belay device. A short piece of thin cord wrapped around the rope can grab it at that moment and hold you in place. Climbers in Taiwan mostly call this cord a "prusik", whether the hitch tied with it is a prusik or an autoblock. It's also basic self-rescue gear: ascending a rope, building a hauling system and escaping a belay all rely on two of these loops.
This post answers one question: which one to buy. For how to tie the hitches and rig a rappel backup, see Lower or rappel? and Self-rescue basics; for how it fits into multi-pitch, see Multi-pitch basics. By the end you should be able to decide whether to cut and tie your own cord or buy a sewn loop, and pick one or two from the tables below.
Two routes: tie your own or buy sewn
Tie your own: buy a length of nylon accessory cord sold by the metre and join the ends into a loop with a double fisherman's. It's cheap, you choose the length, and when it wears out you cut a new piece. Petzl's method uses 1.5 m of 6 mm cord (Petzl Tech Tip), and its instructions require a double fisherman's to join it (Petzl CORDS). The downsides: the knot takes up some length, a badly dressed knot can loosen, and you have to confirm the strength yourself.
Buy sewn: the manufacturer stitches the ends together into a fixed-length loop. With no knot, it sits more neatly on the rope; many use heat-resistant aramid, and a few state outright how thin a rope they work on. The downsides: they cost more, the length is fixed, and if you buy the wrong length you have to buy another.
Both routes are safe. Which one fits depends on how thin your rope is and what kind of routes you climb. The criteria below tell you which way to go.
Something you can do tonight: dig out your rope and read the diameter on the label at the rope end. Every criterion below compares against that number.
Four criteria
1. Diameter: always judge it against your rope
A friction hitch works by a thin cord wrapping tightly around a thicker rope. If the cord is too thick, it can't wrap tightly enough to grip; too thin, and it grips so hard it's difficult to slide, and it's more easily damaged by heat and abrasion. So cord diameter always has to be judged against the rope.
Climbers often say "2–3 mm thinner than the rope". No manufacturer puts it that way; the source we found is AAC's 2013 "Know the Ropes: Lowering", which calls it a "general rule" (AAC). Versions online differ too:
- IFMGA guide Dave Searle says roughly half the rope's diameter.
- Some instructional sites say two-thirds of the rope's diameter.
Manufacturers only give absolute numbers:
- Petzl: 6 mm cord for a prusik loop. It only says the two diameters must differ "enough", with no ratio (Petzl Tech Tip).
- Sterling HollowBlock2: a 6.8 mm loop, stated for ropes 7 mm and up (Sterling).
- Beal Jammy: comes with a table for 7.3–10 mm ropes that adjusts by loop length and number of wraps, not by changing diameter (Beal).
- BlueWater VT Prusik: the 7 mm version for 8–9.5 mm ropes, the 8 mm version for 8–13 mm (BlueWater).
So use "2–3 mm thinner" as a starting point: on a 9.5–10 mm rope, 6 mm nylon accessory cord is the most common combination. On a thin 8.5–9 mm rope, the diameter gap with 6 mm nylon gets small; at that point a sewn loop whose maker lists a thin-rope range takes the guesswork out.
The thinner the rope, the more likely the backup won't grip. The German Alpine Club (DAV) put it plainly in its 2020 rappelling safety research: the thinner the rope, the more likely the backup fails to react; if a prusik doesn't grip, add a wrap (DAV Panorama 4/2020).
Something you can do tonight: wrap your cord or loop around your rope in a three-wrap prusik and pull down on it with your body weight. If it doesn't grip, add a wrap, and note how many wraps this cord and rope combination needs.
2. Material: nylon, aramid, Dyneema
On rappel, the rope rubs through the belay device and heats up. A prusik sits right against the rope, so how well its material handles heat matters.
- Nylon: most accessory cord sold by the metre is nylon (Edelrid's current PES CORD is polyester, the exception). It's soft, wraps easily and is cheap. A Climbing.com article by an AMGA guide warns that nylon exposed to heat can glaze (the surface turns shiny and stiff) or even melt (Climbing.com, 2019).
- Aramid (Technora, Kevlar): heat-resistant, used in Sterling HollowBlock2, Beal Jammy and Edelrid Aramid Cord Sling. It has three downsides: it's stiffer; it degrades in UV, and Sterling says three months in the sun can cost up to half its strength (Sterling, 2023); and it weakens with repeated bending.
- Dyneema (HMPE): a low melting point (Beal gives 145 °C) and a slippery surface. Beal's 100% Dyneema 5 mm cord states explicitly that it must not be used for prusik-type hitches (Beal).
But aramid isn't automatically better. DAV's 2020 tests found that stiff, aramid-core cords reacted noticeably worse than soft cords (the soft cords DAV compared against had a sheathed Dyneema core, not the bare Dyneema cord Beal forbids for friction hitches above), and in dynamic tests the stiffer, thicker cords failed several times. One of the accidents they analysed involved a "relatively stiff 6 mm cord". In the same study, the best reaction came from a 30 cm sewn Dyneema sling tied as an FB crossed hitch. Edelrid also lists its HMPE cord sling, which has a polyester sheath, as usable as a prusik loop (Edelrid).
So read the materials like this:
- "No friction hitches on Dyneema" refers to bare Dyneema cord, and the manufacturer says so explicitly. For HMPE loops with a sheath, go by what the manufacturer says.
- Aramid buys heat resistance at the cost of stiffness. Once you buy one, test it on your rope first; if it doesn't grip, switch models or add wraps.
- For your first one, nylon won't steer you wrong.
Something you can do tonight: run your fingers along your prusik. If any section is shiny, stiff or noticeably slick, it has been heated. Replace it.
3. Length and wraps
Length decides two things: how many wraps you can get, and how far the loop extends when it hangs from your harness.
- Tied prusik loops: Petzl uses 1.5 m of 6 mm cord tied into a loop. The 2019 Climbing.com article uses 40 inches (about 1 m) of 5 mm cord; tied into a loop, it fits over your head with a helmet on.
- Sewn loops: HollowBlock2 comes in 13.5 and 19 inches; Beal Jammy in 35, 50 and 60 cm; for Edelrid Aramid Cord Sling, the manufacturer only says the 30 cm version suits use as a prusik loop.
- When it's too long: on rappel the autoblock is clipped to your leg loop, and a loop that's too long can get pulled up into the belay device; once it touches the device, it slips. AAC's IFMGA guide Rob Hess warned about this (AAC, 2012), and the practice scenarios in Lower or rappel? include this situation.
Wraps are tied to length, and they depend on the rope, the loop and its material. Dave Searle starts from a baseline, adds a wrap if the hitch doesn't grip and takes one away if it's too grabby; he says only testing tells you, and suggests trying it at home on a single and a double strand to work out how many wraps your loop needs on your rope with your body weight plus gear (Dave Searle, 2025). Short Guys Beta Works also says the number of wraps depends on the thickness of the rope and the cord and on the cord's material, and tests the hitch in both directions before trusting it (Short Guys Beta Works, 2024). A loop that's too short leaves no room to add a wrap.
Beal's table is the only manufacturer data that puts this into numbers:
| Jammy length | Rope 7.3–8.1 mm | Rope 8.1–10 mm |
|---|---|---|
| 35 cm (doubled Prusik) | 3 wraps | 2 wraps |
| 50 cm (doubled Machard) | 5 wraps | Manufacturer recommends a longer one |
| 60 cm (doubled Machard) | Manufacturer recommends a shorter one | 8.1–8.6 mm: 6 wraps; 8.6–10 mm: 5 wraps |
Something you can do tonight: girth-hitch your prusik to your harness belay loop, pull it straight, and see how far it reaches. If it reaches past where your belay device sits, it's too long.
4. Strength and certification
A prusik isn't meant to catch a full lead fall, but it does take load in a rescue, so it still needs to be strong enough.
- Accessory cord sold by the metre falls under EN 564. Most 6 mm nylon accessory cord is rated 7.5–10 kN. Knots reduce strength: Petzl says a knot can cut strength by half (Petzl CORDS); Beal publishes the strength of a loop tied with a double fisherman's, 11.5 kN for 6 mm (Beal).
- Sewn loops fall under EN 566. Beal Jammy, Edelrid Aramid Cord Sling, Fixe Tou Aramid and Simond Autoblok all state 22 kN, EN 566. Sterling and BlueWater don't state a certification for their climbing models.
- Be careful with 5 mm: Sterling classes its own 5 mm accessory cord as "not for life-safety use", and Mammut lists its 5 mm for tying down packs and guylines. If you want 5 mm, choose one the manufacturer says can be used as a prusik.
Something you can do tonight: check whether your accessory cord is marked EN 564. If it isn't marked and you don't know where it came from, don't rappel on it.
Sewn loops: 8 models
Only climbing models still sold on the manufacturer's site on 2026-10-24 are included. Prices are the manufacturer's listed price that day; where the manufacturer lists none, one retailer is given and noted. "Rope range stated" quotes only the manufacturer's wording; if they don't state one, it says so.
| Model | Diameter / material | Strength / certification | Length | Rope range stated | Price | Who it suits / downsides |
|---|---|---|---|---|---|---|
| Sterling HollowBlock2 | 6.8 mm / 100% Technora hollow braid | 14 kN / not stated | 13.5, 19 in | 7 mm and up; prusik, Klemheist | USD 29.99–30.99 | Works for multi-pitch and thin double ropes; lower strength than similar loops, and the maker says not to use it as a primary attachment point |
| Beal Jammy | about 5.5 mm (retailer listing) / aramid + polyamide sheath | 22 kN / EN 566 | 35, 50, 60 cm | 7.3–10 mm, with a wraps table | EUR 13.88–17.09 | For people who want to pick length from a table; you have to buy the right length for your rope |
| Edelrid Aramid Cord Sling 6 mm | 6 mm / aramid | 22 kN / EN 566 | 30–120 cm (30 cm as a prusik loop) | Not stated | Not listed by maker; no in-stock retailer found on the check date | Cheap and heat-resistant; the maker itself says it's very stiff |
| Fixe Tou Aramid Sling | 6 mm / polyamide sheath + aramid core | 22 kN / EN 566 | 30–180 cm | Not stated; Machard and Prusik named | Not listed by maker; retail Bolas Sport EUR 13.95–15.95 | The maker says the prusik suits stiff or icy ropes; lengths are inconsistent across the maker's page |
| Simond Autoblok 60 cm | 6 mm / aramid core | 22 kN / EN 566 | 60 cm | "Even the thinnest ropes" | GBP 12.99 | Cheap, 30 g; only one length, and the maker's page contradicts itself on the sheath material |
| Sterling 6 mm Auto Block | 6 mm / not stated | 12.5 kN / not stated | 13.5 in | Not stated; prusik, Klemheist | USD 18.99 | Sterling's cheapest loop; material and certification not stated, strength at the low end of the table |
| BlueWater Sewn Prusik Loop | 6.5, 7, 8 mm / not stated | 12.4–17.7 kN / not stated | 11–68 in | Not stated | USD 16.14–22.06 | Widest choice of diameters and lengths; material and rope range not stated |
| BlueWater VT Prusik | 7, 8 mm / Technora sheath + nylon core, open ends | 7 mm end to end 2,500 lbf | 33 in | 7 mm version 8–9.5 mm; 8 mm version 8–13 mm | USD 30.95–37.95 (8 mm black version 37.95) | Clearest stated rope range; you need to know VT and Schwabisch-type hitches, and it's the most expensive |
Not included: Grivel Magic Ring (removed from the manufacturer's site); Petzl doesn't make its own sewn prusik loop; Beal Back-Up Line is a 50 m rescue rope, not a loop. Sewn 8 mm loops for arborist and rescue work (Sterling Bound Loop, Edelrid Tibor and others) aren't positioned by their makers for climbing, so they're left out.
Accessory cord by the metre: 10 models
For tying your own. Mainly 6 mm, plus 7 mm and purpose-made cords where the maker states prusik use.
| Model | Diameter / material | g/m | Strength / certification | How it's sold | Price | Does the maker say it can take friction hitches? |
|---|---|---|---|---|---|---|
| Sterling 6 mm Accessory Cord | 6 mm / nylon | Not stated | 8.2 kN / EN 564 | From 25 ft | From USD 19.99 | Yes: 6–8 mm suits prusiks |
| Sterling 7 mm Accessory Cord | 7 mm / nylon | Not stated | 12.3 kN / EN 564 | From 18 ft | From USD 22.99 | Yes |
| Mammut 6.0 Cord 7m | 6 mm / polyamide | 22 | 7.5 kN / EN 564, UIAA | 7 m piece | USD 17.95 | Yes: "ideal for tying a prusik knot" |
| Beal Cordelette 6 mm | 6.1 mm / polyamide | 22.8 | 8.2 kN (11.5 kN tied as a loop) / EN 564, UIAA | 5.5 m × 10 pieces, 120 m | GBP 80.27 / 10 pieces | Not stated |
| Petzl CORDS 6 mm | 6 mm / nylon | 24 | 10 kN / EN 564 | 120 m spool only | Not listed by maker; retail Karst Sports USD 140.95 / 120 m | Instructions: join prusik loops with a double fisherman's |
| BlueWater 6 mm Accessory Cord | 6.1 mm / nylon | 24.9 | 9.1 kN / CE, UIAA | From 30 ft | From USD 15.95 | Not stated |
| BlueWater Dynamic Prusik Cord | 6.5, 7, 8 mm | 26.3–39 | 9.3–11.1 kN / not stated | 60 m only | From USD 119.95 | Yes: designed for prusiks, holds more force before slipping |
| Maxim Prusik Cord | 5–9 mm / nylon | 25.3 (6 mm) | 7.8 kN (6 mm) / EN 564 not stated | By the foot | From USD 0.58 / ft | Yes: purpose-made |
| Singing Rock Accessory Cord 6 mm | 6 mm / polyamide | 23.2 | 9 kN / EN 564 | 100 m only | Not listed by maker; retail fallprotection.cz EUR 117.04 / 100 m | Not stated |
| Edelrid PES CORD 6 mm | 6 mm / polyester | 30 | 9 kN / EN 564 | From 8 m | Not listed by maker; retail Bergfreunde from EUR 14.36 | Not stated |
In Taiwan, accessory cord sold by the metre is usually cut from a spool at an outdoor shop. When you buy, ask which brand and diameter it is, and only use it once you've been able to look up the specs at home.
Heat-resistant cord: if the maker doesn't say it takes hitches, don't use it yet
There's a category of "tech cord" with a Technora core and a nylon or polyester sheath, such as Sterling PowerCord 5.9 mm, Maxim Tech Cord and Edelweiss Aramid Cord. They're very strong, but their makers position them for building anchors and hauling, and the product pages don't say they can take friction hitches.
Where the manufacturer is silent, this post won't fill in for them. If you want a heat-resistant prusik, pick an aramid model from the sewn-loop table whose maker explicitly says it takes hitches.
Test and review videos
Written reviews are scarce; videos are more plentiful. Below are three, all uploaded in 2024 or later, each covering specific models, and each checked against its transcript.
From 8:58, IFMGA guide Dave Searle compares four kinds of cord. The Beal Jammy 60 cm is his own go-to, and he carries two when guiding; 6 mm nylon is cheap but stiffer, and doesn't grip as well as the Jammy; HollowBlock2 is hard to find in Europe and is certified differently from the Jammy; Dyneema is too slippery and not heat-resistant enough, so he doesn't recommend it as a rappel backup. He also gives a rule of thumb for length: 35–40 cm is the minimum, and ideally no more than 60 cm. From 19:53 he covers wraps: add one if it doesn't grip, take one away if it's too tight, and test it at home with your own rope. The description promotes his own online courses; there's no gear sponsorship.
Climbing Clean introduces the Beal Jammy 5.5 mm, HollowBlock 6.8 mm and BlueWater VT 8 mm side by side; it's the only video we found that covers all three together. From 3:54 he says the HollowBlock grips better on thick ropes, and that he uses the VT almost only for rescue. These are impressions from use, with no measurements; the description has no sponsorship or affiliate links.
Jason of Short Guys Beta Works compares the six friction hitches he uses most, demonstrating with a Sterling HollowBlock2. From 0:34 he covers the autoblock, which he uses as a rappel backup: how many wraps it needs depends on the thickness of the rope and the cord and on the cord's material, so he always tests it in both directions before trusting it. It's the least grabby of the set, which can be a plus for a rappel backup, but you have to find the number of wraps that catches in an emergency without making it hard to feed rope through the rappel. From 1:44 he says the traditional three-wrap prusik typically works with standard cord diameters on most climbing ropes. From 4:45 he notes that Dyneema has a low melting point and is slippery, so it's not a good material for any friction hitch to begin with. The description says it may contain affiliate links.
Among Chinese-language videos, we found none from Taiwanese or other Mandarin-speaking climbers comparing specific models, only tutorials showing how to tie a VT prusik.
Choosing for three kinds of use
Single-pitch at Longdong, with the occasional rappel
(Longdong is Taiwan's main sea-cliff sandstone crag, on the northeast coast.) Ropes there are mostly 9.5–10 mm.
- Buy 1.5 m of 6 mm nylon accessory cord, tie it with a double fisherman's, and make two. One 7 m Mammut 6.0 Cord is enough for several.
- Practise first in the gym or on the ground until every wrap comes out equally neat. DAV says the strength of messily wrapped prusiks varies "enormously".
Multi-pitch, or a thin 8.5–9 mm rope
- Choose a sewn loop whose maker states a thin-rope range: Beal Jammy (pick the length from the table), Sterling HollowBlock2, or BlueWater VT 7 mm.
- Test an aramid loop on your own rope when you get it; if it doesn't grip, add a wrap; if it still doesn't, switch to something softer.
- Carry two: one for the rappel backup, one for self-rescue.
Preparing for self-rescue
- Two prusik loops are the minimum. The gear list for the rescue course at ZA Adventure, a Taiwanese climbing school, requires two (see Self-rescue basics).
- Have one longer loop (for an autoblock or Machard) and one short one (for a prusik), and practise with both lengths.
Inspection and retirement
- Look it over before every use: if the surface is shiny and stiff, partly melted, the sheath is torn, or a section feels noticeably harder or thinner, replace it.
- Sewn loops: Sterling says a HollowBlock2 must be retired if any single yarn is cut, the stitching is abraded, or the plastic protective sleeve is missing (Sterling, 2023).
- Keep aramid out of the sun: when you're not using it, put it in your pack rather than leaving it hanging on your harness in the sun.
- Nylon accessory cord: manufacturers give no quantified retirement criteria. It's cheap, so if in doubt, cut a new one.
For full inspection and retirement rules, see the last post in this series, How to inspect and retire climbing gear.
Practice: three scenarios
Answers are under each question. Think first, then look.
1. You've just bought an 8.9 mm triple-rated thin rope for multi-pitch, and your prusik is 7 mm nylon accessory cord you cut last year.
Answer
The diameter gap is only about 2 mm, so it may not grip. Test on the ground first: tie three wraps and pull; if that's not enough, go to four. The more reliable option is a loop whose maker states a thin-rope range, such as BlueWater VT 7 mm (8–9.5 mm), or a Beal Jammy with the length picked from its table.
2. A friend gives you a spool of 5 mm Dyneema cord, says it's strong and light, and tells you to cut it into prusiks.
Answer
Don't. Beal states explicitly that 100% Dyneema cord must not be used for prusik-type hitches; its melting point is around 145 °C and its surface is slippery. High strength doesn't mean it works as a friction hitch.
3. Halfway down a rappel, you notice your autoblock keeps getting dragged up against the belay device, and the backup doesn't seem to be doing anything.
Answer
Stop. An autoblock pressed against the belay device slips, so right now it isn't protecting you. Next time use a shorter loop, or extend the belay device so the two stay apart; see Lower or rappel? for how.
Next
The prusik is the last of the "cord" gear. The next post moves into trad protection: post 10: Nuts.
References
Manufacturer product pages and prices (checked 2026-10-24) are linked in the tables above.
- How to make a Prusik loop for a rappel backup? (Petzl Tech Tip)
- Friction hitches (Petzl Tech Tip)
- CORDS (Petzl)
- Know the Ropes: Rappelling (Rob Hess, AAC, 2012)
- Know the Ropes: Lowering (Mike Poborsky, AAC, 2013)
- Retirement Guidelines for the HollowBlock 2 (Sterling, 2023-11-02)
- Jammy (Beal)
- 100% Dyneema 5 mm (Beal)
- HMPE Cord Sling 6 mm (Edelrid)
- Sicherheitsrelevantes zum Abseilen (DAV Sicherheitsforschung, Panorama 4/2020, in German)
- Gym to Crag: How to Tie Friction Hitches (Climbing.com, 2019)
- Friction Hitches for Climbing and Mountaineering DEEEEP DIVE (Dave Searle, 2025-08-27)
- PRUSIKS!!! Beal jammy, hollowblock, and VT (Climbing Clean, 2024-03-03)
- Six Climbing Friction Hitches and Their Pros and Cons (Short Guys Beta Works, 2024-09-09)