Grover Professional Mandolin Machine Heads 309FN, Standard 4 + 4, For &ldquo;F&rdquo; style Mandolins, Nickel F-type Deluxe Mandolin Tuners 18:1 ratio, Nickel with Pearl buttons, Worm over gear Designed by master luthier Lynn Dudenbostal Item Number: 309FN Available at Ant Hill Music!