Constructed from investment cast steel for durability & toughness, the BBT-16 fits 16mm hex-hole caps, such as those found on Truvativ cranks, for quick & easy loosening & tightening during removal & replacement. The tool is equipped with an 8mm hex hole of its own which will allow you to add leverage in the form of a suitable hex wrench or Allen key when tackling those tricky to remove, hard-fastened caps. A great device that makes an essential job that bit easier, the Self-Extracting Crank Cap Tool BBT-16 is a brilliant bit of kit from Park Tool.