The D'Addario 3 + 3 format Auto Trim Tuning Machines are precision tuners that automatically cut the excess string while changing strings, eliminating the need for string cutting tools and making string changes easy and fast. The 18:1 ratio worm gear construction ensures greater precision than standard tuners and ensure tuning stability even during the hardest playing. Includes 6 tuners and mounting hardware. Black finish. 3 + 3 design for instruments that have 3 tuning machines on each side of the headstock. Ordinarily, restringing is a tedious chore, requiring extra tools such as string cutters in order to get the job done. Auto-Trim tuners eliminate this need by automatically trimming the excess string from the tuning post as you increase the tension on the string. The Auto-Trim's rugged, die-cast housing and precision machined 18:1 bevel and worm gears assure in-tune performance after even the most aggressive playing or tremolo use. The tuners include a string clamp that securely hold the string in place, eliminating the need for multiple wraps around the tuning post. Simply insert the string, tighten the clamp, tune it up to the proper tension and allow the auto-trim feature to remove the excess string. Changing strings has never been easier. A Ned Steinberger Design.