Constructed from investment cast steel for durability and toughness, the BBT-16 fits 16mm hex-hole caps, such as those found on Truvativ cranks, for quick and easy loosening and tightening during removal and 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.