An elegant, simple design for ascending ropes. Now with a nice a plastic widget that helps set the teeth into the rope. Use with a large-rod-stock carabiner like the BD RockLock. Very lightweight and handy to have. Fits on ropes 8mm to 11mm, works pretty well on my 6mm pull cord. The downside: sharp teeth can tear up the rope, and it is very hard to move DOWN the rope, for instance when changing back to rappel mode. This is probably the best choice to carry as an emergency ascender. Superlight and compact, not too pricey, and it does not wear out. Also useful for hauling packs and stuff like that. 

BUT: not good on actual 8mm ropes. Very hard to get it grip => tears up the sheath when it does not work. If using the really nice, expensive, modern top-of-the-line ropes, then you definitely can afford a Petzl Basic and MicroTraxion for your ascending kit, to avoid tearing up the rope.