Precision Tuning with Zero Slippage in a Mid-size Tuner These 305BC Mid-Size Rotomatic tuners offer that tried-and-true Grover quality guitarists have grown to love, presented in a sleek and stylish black chrome finish. Slightly larger than the Mini Rotomatics, the Mid-Size series features smooth, precise tuning for each string courtesy of an 18:1 gear ratio. GearNuts guitarists love the enclosed gear box design that permanently lubricates each machine head, offering endless playability and minimal trouble. Precision-cut worm and gear serve up perfect meshing, eliminating backlash and slippage. Each set comes with 5/8-inch washers, bushings, wood screws, and — as always — Grover's lifetime warranty.Grover: exceptional quality and lifetime warranty Grover has been keeping the world's finest stringed instruments in tune for over a century. Grover started out in the late 1800s producing banjo and guitar tuning machine heads. Eventually, the company expanded into making tuners for mandolin, dulcimer, ukulele, violin,