Kluson's newest addition to the Supreme series tuning machines. Based on the original Kluson deluxe stamped steel tuning machines, the Kluson Supreme Series tuning machines are the next generation in stamped steel design for your mandolin.Using original Kluson 4 per plate mandolin tuning machine mounting specs, the new Supreme mandolin tuning machines look almost identical to the originals with the exception of the Kluson Supreme series name in double row appearance on the housing.You will immediately notice increased performance, fine tuning stability and a super smooth feel. By incorporating steel string posts, correct-sized round mandolin buttons and the addition of a high 18:1 gear ratio this is a real game changer. Options include simulated bone, black and simulated white pearl buttons in nickel or gold plating for both A and F style mandolins. Includes all mounting hardware. Post to Post spacing= 59/64 in. (23.33mm) End to End mounting hole Ctr to Ctr= 3 11/16 in. (93.78mm) Mounting Hole spacing end to middle, ctr to ctr= 1 27/32 in. (46.75mm) Overall Post length= 1 in. Post Length from baseplate to flat top= 31/32 in. String Thru Ctr height on Post= 51/64 in. (20.35mm) Gear Ratio= 18:1 Gear Material= Brass ring, Steel Worm Bushing O.D.= 11/32 in. (8.8mm) String Post Diameter= 1/4 in.