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Built from Sterling's RIT 900 cord, the Hollow Block 6.8mm x 13.5in is designed to function as a pre-sewn prusik or climb heist. Made with aramid fiber and sewn with Sterling's proprietary sewing pattern, this ultra-strong cord is designed to provide excellent griping power on climbing ropes with diameters of 7mm or larger.

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A must-have!

  • Familiarity: I've used it several times

If you're a climber and looking to rappel (this applies to canyoneering too!), then you'll want this on your harness before you step over the edge. If you set these up as you're third hand, you can rappel with peace of mind. They are very, very grippy, so that can be both a blessing and a curse. If you're attached to the yellow color, don't be because these will quickly become brown from use. That is only aesthetic though, but just a forewarning!

Pretty nice tool

  • Familiarity: I've used it once or twice and have initial impressions

I've only used a hollow block a few times. But it is a very interesting way to descend from a climb. After tying a prusik on your brake hand end of the rope and you've attached it to yourself you're good to go. It acts as an auto lock on your repel, which enables you to clean gear and take both hands off the rope (sketchy!) or fix the rope that's been tied into a mess. It's a inexpensive piece of gear but can make a tough repel easier with a little peace of mind. I'd recommend this to any climber, or canyoneerer looking to up their safety.

I prefer 6mm prusik cord

  • Familiarity: I've used it several times

Although the Hollow Block works very well as a rappel back-up, it got dirty-looking very fast and did not shield my brake hand from heat build-up as well as my trusty, cheap 6mm prussik cord. The 13.5" length worked well for me.

Perfect webbing

    I bought this for a prusik when rapping down icy or wet conditions when canyoneering. The cord is very sturdy, and the pre-sewn device makes it super easy to attach to the rope. That being said, this is very burly, and will definitely slow you down. I would definitely recommend figuring out if you need the 13" or 19" version, as the 13" is pretty short, and depending on your needs, you may want to consider the 19".

    don't leave the ground without it

    • Familiarity: I've used it several times

    Ties into a perfect Klemheist or Autoblock in about 10 seconds. Slides easily on two 10.1mm ropes, but grips tightly when you let it go.

    I set up my rappel device at the end of the first loop of a Sterling Chain Reactor, and connect my friction knot to a small locker attached to my belay loop. For that setup, I prefer the shorter (13.5") length. Long enough to get 3 turns, short enough there's no way it can jam my device.

    Really grippy, maybe too grippy

    • Familiarity: I've used it once or twice and have initial impressions

    I always use a prussik as a backup on my rappels, so I was excited to buy a dedicated piece of gear for that purpose. I ordered the 13" version, but I think I would have preferred the 19"; I should have measured my existing prussiks before ordering.
    The hollow block is definitely burly, and the bar tacks are strong - I never doubts its strength. It's also relatively easy to work with when wrapping the rope, although, again, I think I would have preferred the 19" version.
    The first time using it, I was rappelling on my 10.2mm rope, which I've had for a few years (it's slightly fuzzy, not too bad). I set the hollow block up as a prussik (rather than some other friction hitch), and I found it difficult to keep moving as I rappelled. I think this was a combination if it being too short, which kept the rope too close to the brake position, and too grippy, which made it difficult to slide smoothly.
    The second time I used it, it was on my friends 10.0 rope, which was less used. It was a lot more manageable this time around, and slid smoothly. However, neither time did it slide as nicely as my simple prussik made from 6mm accessory cord.
    All in all, I'll try using it some more (maybe it will "break in"), but my first instincts were to just go back to the cord I normally use.

    Pretty simple

      Love the this piece of hollow block. I have the 19. i use it mainly as it is intended but the extra length does allow for some versatility. The Prusik is a simple concept that can save your life. If you are not using one, you should reconsider.

      Best friction hitch loop on the market

      • Familiarity: I've used it several times

      It bites anything, feels bomber, and bundles up well to stash on your harness, since it's a "hollow" weave with a bar tack instead of a bulky fisherman's knot. I got the 13.5" as a rappel back-up, which is a hair long if you do three wraps and attach it to your leg loop. Even if you think the heat resistance is superfluous, this little guy bites better and handles better than any bit of string you might buy off a spool. My only criticism is that after a little bit of use it'll look filthy from sliding along your filthy ropes....maybe that's an additional anti-theft feature!

      Awesome Product

      • Familiarity: I've used it several times

      I love this product. A guide let me use theirs this summer on some routes in the Tetons and they make for an excellent prusiks, but can also be used as a full strength sling. It's now a standard in my kit. There is a ton of information online about it's strength, but you only need to use it once to know how bomber it is.

      Great prusik

      • Familiarity: I've put it through the wringer

      Stirling's RIT material grips exceptionally well, freakishly well compared to normal 6mm accessory cords.

      Both lengths are too long for backing up a rap when your device is not extended away from your body with a sling of some kind... If you lift up a leg with the prusik it can come up and jam in the device... However everyone should be extending their devices when rapping anyways so this shouldn't be an issue. (You can turn a quad length sling into a handy combo rap extension + 2 attachment point lanyard to greatly speed up multipitch raps.)

      This material makes an excellent rescue loop. I have not tried to use it with prusik minding pullies however. High strength makes it also double as a runner if needed for extending protection.

      Really, this stuff is awesome. I hope Stirling goes on to make some other similar products sing this material or ones inspired by it.

      Safest autoblock, period.

      • Familiarity: I've put it through the wringer

      Want supreme confidence when rappelling? The hollow blocks grabs any diameter cord amazingly well. It also slides easily and doesn't seize, something I've experienced with icy prusiks.

      Three wraps is all you need, but you can easily add more with the longer version. Amazing design, absolutely perfect, as far as I'm concerned a MUST HAVE. I always have mine.

      Great addition

      • Familiarity: I've put it through the wringer

      Very helpful as autoblock. Comes in handy a lot. Ive used it to take the weight of my rope when soloing and I needed a minute before continuing. I cant even begin to list all the things you can do with a piece like this. I am always glad I have it, I highly recommend.

      Highly Recommend

      • Familiarity: I've put it through the wringer

      I agree completely with previous reviewers; these things are GREAT! I use them exclusively for autoblocks during rappels and klemheists when rigging leveraged haul systems (think rescue) and other types of backups. They function well for prusiks too, it's just not a knot I use often (prefer klemheist). Work very well for canyoneering and last a long time. Yes, a piece of 6mm tech/accessory cord with a dbl-fishermans does the same thing...this is just too easy, light and cheap not to own. Plus you get the added heat benefits of using aramid for your backups. just get one and try it.

      Strong and Grippy

      • Familiarity: I've put it through the wringer

      It's nice that this cord will withstand high heat, however, my main concern with a prusik cord like this one is how well it grips. This cord clearly grips well and is strong. You can rely on it when you're rapping off very steep or overhanging rock. I recommend this over any other prusik cord.

      Heat resistent

      • Familiarity: I've used it several times

      The main advantage of this prusik over others is that the aramid (Kevlar?) material is highly heat resistant. This allows you to run rope through it very fast and not worry that the heat has damaged the strength of the cord.

      I believe Sterling's specs indicate that it will withstand over 900 degreed F (probably why its called the RIT 900).

      Plus its light, handles well, and grips well.

      Grabs Anything

      • Familiarity: I've put it through the wringer

      I take this thing everywhere; I bought 2 more to replace the one I have had for the last 3 years. I bring it on every climbing trip while guiding and for my personal adventures. It wraps and grabs any rope of any diameter. Rappelling with double 10.5mm, it grabs and can still be managed with one hand; Simul-rappelling on a 9.5mm, it grabs w/ only 3 wraps and still gives you lots of control.

      NOTE: When using a "third-hand," it is safer to extend your ATC (with nylon not pure spectra) and put the autoblock on your belay loop with a locker.

      Question: Is the size (13.5 or 19) the "circumference", the length before it was sewn, or something else? thx

      Is this the 13.5" or the 19"? The description says 13.5", the style/size dropdown says 19".

      You can choose either size, in the drop down menu.

      If it's not giving you both options, there is either a technically difficulty, or we have sold out of one size. At this moment, we have plenty of both sizes.

      Questions? Reach me directly at:

      Emily Jenson

      Expert Gearhead


      How UV-stable is this aramid, compared to...

      How UV-stable is this aramid, compared to nylon?