These guitar machines are a triumph in engineering and styling. The housing provides a maximum bearing for worm, gear and string post. Gear ratio is 14:1. Worm and gear are precision-cut for perfect meshing. This eliminates backlash and slippage. Countersunk tension screw permits player to regulate turning tension to any degree. Gear box has a special lubricant for lifetime, trouble-free service. Includes 5/8" washers, bushings and wood screws.For standard guitars, Set of 6 (102N Nickel), (102C Chrome), (102G Gold), (102NK Nickel), (102CK Chrome), (102GK Gold)-Button Type = Grover kidney shape-Gear ratio = 14:1-Post Height = 1 1/16 in. (27mm)-Post Diameter = 15/64 in. (6mm)-Peghole Requirement = 25/64 in. (10mm)-Bushing O.D. = Hex head 9/32 in. (7.8mm)-Bushing I.D. = 1/4 in. (6.3mm)-Collar Height = 25/64 in (10mm)-Collar width = 25/64 in. (10mm)