Seat of 6 quality sealed black right handed machine heads, fit 10mm(0.39inch) standard machine head hole. Heavy duty internal gear tested, easy to install, compatible with steel string electric guitar or acoustic guitar. Gear ratio: 1:14; Zinc alloy material with black plating;Location: 6R; Head size is 22mm(0.87in) width. For specific dimensions, please look at the size diagram. Package includes: 6 x right hand guitar machine heads; 6 x ferrules; 6 x screws; 6 x threaded bushings. 100% brand new and testing is fine.