Brilliant Piece of Design
The Petzl Tibloc is a brilliant piece of design, although it is often misunderstood or misused. Its main purpose is as an emergency, lightweight ascender for climbing up ropes, like in the case of a crevasse fall or ascending a short bulge. These are NOT intended for thousands of feet of jugging (climbing ropes) or as a replacement for a Prussic cord on your glacier kit. Due to the aggressive teeth, if you fell on a Tibloc, you could easily tear the sheath on a rope, so these are for ascending only. They are perfect for times when you think you might need to ascend a rope (crevasse fall, tough climb that you might not make it up, canyoneering), but don't want to carry a full-on ascender.