Mastery Bridge M1 Jazzmaster / Jaguar The condition is good. M1 specification with a bridge foot hole diameter of "0.310 inches (approx. 7.874mm)". ■ Bridge for Jaguar / Jazzmaster, Mustang ■ USA standard ■ String spacing (E to E): 52mm ■ Mastery Bridge is a replacement bridge that can be installed on Jazzmaster, Jaguar, Mustang, Bass VI, Jag-Stang, and Telecaster models equipped with a Bigsby tremolo. It prevents the strings from coming off the saddle even during intense playing, and also achieves a beautiful, resonant tone that makes the most of the entire guitar.