Note first: If you have used a standard ascender/jumar, etc. this thing makes sense. If you haven't, what happens is this: You place the Ti-Bloc against your rope so the teeth point in towards the sheath and the direction you DON'T want it to go (i.e. if you are ascending a rope, the sharp ends point down). The string a biner through the pair of holes. When you pull down on the biner, the teeth push into the rope's sheath, and the Ti-Bloc, and anything attached to it, remain fixed in place.
First, anything by Petzl is good. Can't say enough about this little guy. A Ti-bloc, a prussik, and a couple locking carabiners will get you out of alot of jams. Went and finally practiced self-rescue and it was handy. It's a bit tricky in a self-rescue situation to thread a biner through the Ti-Bloc with one hand (assuming you're holding an injured leader with your brake hand), but thats more a personal dexterity issue than a Ti-bloc issue.
An illustrative story: Devil's Tower. Just purchased my Ti-Bloc ($21 Neptune Mountaineering, Boulder, Colorado) before driving up. As this trip was "Mellow" we did not bring aid gear, ascenders and all that, but the very light Ti-bloc was still on my harness. In the parking lot, some climbers who needed to get as stuck rope down asked for ascenders, and I got out this little marvel which they quickly retrieved their rope with.
The point is this: Ti-blocs weight-to-Usefulness ratio is huge (meaning good).
With a locking biner I have jugged/ascended many rope lengths with no problem.
TIBLOC A small, lightweight rope clamp grab for emergency use This is the smallest and lightest rope clamp grab on the market. It will get you out of ...More at eBay
The Petzl Tibloc is multifunctional: for rescues, hauling systems and rope climbing. Petzl Tibloc Features: Very small and lightweight. Chrome-plated ...More at Oregon Mountain Community
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