D'Addario Auto-Trim Locking Tuning Machines, 6 In-Line setup, BlackThe D'Addario 6 in line Auto Trim Tuning Machines are precision tuners that automatically cut the excess string while changing strings, eliminating the need string clippers making string changes easy and fast. The 18: 1 ratio worm gear constructions ensures greater precision than standard tuners and ensure tuning stability even during the hardest playing. Includes 6 tuners and mounting hardware. Chrome finish. 6 in line setup for instruments that have