Grover 145C Bass Tuners - 2+2 - Chrome 2 per side configuration Chrome SELF ALIGNING THRUST BEARINGS. May be used with ALL modern bass guitar headpieces Gear ratio is 20:1. Special butterfly button. Worm meshes perfectly with gear. Individually hand tested. Durable cast housing. End thrust bearings. Safety-type string with cutaway shoulders to provide slip-over. Two screws in housing apron provide greater holding power. Screws and bushings included