This is a tool for double-locking system bridges. It fits Strat-style electric guitars or other similar style guitars equipped with a Floyd Rose tremolo bridge system. It locks down the strings when using the tremolo arm, preventing them from slipping over the nut and going out of tune. Conveniently installed with hex nuts and screws. Nut width: 43mm E-E center width: 35mm String pitch: 7mm, Radius: 12" (305mm), Mounting screw hole spacing: 14mm