This is a set of four black-button open gear tuners, in a 2-left 2-right configuration. These are economy grade tuners, with chrome-plated metal surfaces and a plastic tuning button. The post length is 1 1/8" plate to tip, and just over 3/4 plate to string hole. Each tuner mounts with two screws, which are provided. These are also great for 3 and 4-string cigar box guitars. Be sure to mount these on the correct side of the headstock, so that the brass gear is towards the body of the instrument, to prevent gear slippage as string tension increases.