Sewn prusik cords are nothing new, but what makes Sterling Rope’s Hollow Block unique is the use of 100% aramid fiber, in the form of their 6.8mm RIT 900 cord.
That sounds like a whole bunch of proprietary gibberish, so let me save you some google time: aramid fiber is a type of synthetic fiber similar to Nomex, the stuff used to make fire-resistant suits. The melting point of this particular cord is 932F/500C (you couldn’t melt this stuff in your oven). Its other unique characteristic is the “hollow braid construction,” which is exactly what it sounds like – the rope is ‘hollow’ on the inside.
Of what benefit is this to climbers?
Think of how hot your belay device gets during repeated, long rappels, and the heat-resistance makes a bit more sense. Though I’ve never melted a prusik cord, I always appreciate extra security and some additional heat-resistance can’t hurt, right?
The benefits of hollow braid construction are harder to see, as I don’t have any of this cord around in non-hollow form to do a direct comparison with. The cord does seem to conform to ropes better than non-hollow cord, and this 6.8mm prusik will grip on 6mm accessory cord (though Sterling says minimum is 7mm). But, yup, 6.8mm and it’ll grip down to 6mm. That’s pretty awesome.
The cord is sewn in Sterling’s proprietary pattern, and I don’t know of what benefit this is. But this little loop is rated to 14kN (about equal to 3100lbs), so while not full-strength (22kN for most climbing applications like slings, dogbones, etc.) it can still be used in limited fashion as a piece of climbing kit. And not having any knots in it makes it much more compact and easier to store. I’ve never used it it any capacity other than a prusik, but I guess you could?!
The sewn bit is protected by a plastic sheath, and the whole package weighs a scant 25 grams, and costs less than $10.
The best bit is that once you put one of these on your harness, you’ll always have an emergency prusik, just in case.
So, it works, it’s light, it’s cheap. I really see no reason not to own one, or two.
Pros: grips on cord 6mm and thicker (7mm officially), costs less than $10
Overall: If you are ever in a situation where you might need to self-rescue, do a partner rescue, need a prusik cord, want a rappel backup, (basically, climb) you should grab one of these. Really, they are that useful.