Smart climbers use a prusik, AutoBlock or klemheist hitch as a back-up when they rappel. Wear and tear from friction means that climbers tend to keep a particular sling just for this purpose that can also be used in progress-capture in hauling systems or belay escapes. Purpose-made sewn prusik slings have been around for a while, but Sterling’s Hollowblock provides some unique features in this simple piece of gear.
The sling is made of Sterling’s RIT 900 cord, which resembles the mantle of a kernmantle rope, sans core. The advantage of this construction is that it maximizes friction on the rope by flattening and conforming to it closely under weight. As such, it will grip on cords down to 7mm.
The aramid fibre material melts at higher heat than many sling materials, so it holds up well in its rope-on-rope, high friction application. At 14kN, the Hollow Block is plenty strong enough for its application, but keep in mind that regular climbing slings are tested to 22 kN, so it is not interchangeable with slings. A great upgrade to a simple, but necessary piece of gear. Available in 48cm and 34cm, MSRP $18.50 and $19.50 respectively.