Our professional “F” Style model mandolin machine heads are the latest in technology. The specially designed, adjustable worm gear along with the die-cast base maintains, the center lines of the gear and worm to ensure correct alignment for the finest tuning possible. Featuring a “rounded washer head” button screw for a more vintage look. The worm to gear ratio is 18:1. Available with either Pearloid, Black, or White buttons. Screws and bushings provided.