Grover 406C6 Rotomatic Mini 6 in Line Self Locking Machine Heads, Chrome Locking Guitar Tuning Machine Heads with Mini-Buttons Completely Enclosed, No need to lubricate Post Height = 1 in. (25.4mm); Post Diameter = 15/64 in. (6mm) Mounting Screw Location = 8 O'clock Gear Ratio = 18:1