Fits some 4-string electric bass, for top-loading and string-through-body combined usage Total string spacing: 19x3mm=57mm (2-1/4 inch), 4 mounting screw holes spacing: 19x3mm=57mm (2-1/4 inch) Made of high density zinc alloy, well finished,stable and durable Saddles lock to base plate for superior sound transfer, better intonation and stability