This bass turner suitable for the open bass tuning keys fit for most 4 string electric bass, very precise, responsive tuning, smooth gearing and stays put, provide finer tuning and greater stability. 4 strings are metal inner , nickel-plated alloy, automatic winding, better increase the brightness, and intensity of the tone. Great for 4 string bass right hand and left hand. Gear:(19mm). Fits string bass, electric bass. The electric bass knobs crafted from metal, unique plum-blossom shaped button, beautiful designed , convenient to rotate and adjust, and the stability is. Package includes opened gear bass tuner peg. Good replacement for most bass and guitar.