The large units have a molded hand grip insert. Two large holes on the bottom of the units will accept most sizes of carabiners on the market. Toothed style cam grips ropes from 5/16″ (8 mm) to 5/8″ (16 mm). The cams are backed by CMI’s guarantee – if you can wear one out, we’ll replace it–free! Designed for a single person to use when climbing a rope, when used in this manner it will not cut or damage the rope. Sold in pairs, one left hand and one right hand. Made in the U.S.A.