These new, professional model mandolin machine heads are the latest in
technology. A specially designed, adjustable worm gear along with the
die cast base maintains the center lines of the gear and worm to insure
correct alignment for the finest tuning possible. The worm to gear ratio
is 18:1. Available in "A", "F", and "F Vintage" styles. Screws and
bushing provided.Standard 4 + 4, For "A" style Mandolins (309N Nickel),
(309G Gold)Standard 4 + 4, For "F" style Mandolins (309FN Nickel),
(309FG Gold)Vintage 4 + 4, For "F" style Mandolins (309FVN Nickel),
(309FVG Gold)