Kluson® 3 Per Side Revolution Series E-Mount Locking Tuning Machines Kluson's® new Revolution E-mount tuning machines are die-cast construction and have the brand new 20:1 gear ratio and are available in both locking and non-locking formats. This all-new Kluson® design incorporates today's standard 10mm peghole mounting with a single screw at 6 O'clock low in conjunction and screw-in bushing and washer. Kluson® designed this new tuning machine type to fit many of the electric and acoustic instruments manufactured post 1970, giving you the option in many cases for a non-modification required upgrade in both performance and appearance. This new Revolution E-mount tuning machine set is available in black, chrome, gold and nickel finishes and all mounting hardware needed is included.[SKU:KREL-3-G] Gear Ratio = 20:1 String Post length overall locking = 27.5mm Center String thru hole height on post = 23mm Locking mechanism = Knob on back of housing Mounting Hardware included Mounting hole placement = 6 O'Clock low String Post material = steel Housing material = die cast zinc Gear material = Steel worm/brass ring