Sperzel Trim-Lok professional guitar tuners. 6 inline for modern Fender® and similar applications. Satin chrome finish. Highest quality machines for fine guitars and demanding players. Turn the thumbscrew on the back of each tuner to lock the string down at the post. The string posts have a staggered height to eliminate the need for string trees. Includes screw-in bushings and face washers. Requires 3/8"(10mm) peghead holes. Single-pin mount. Made in the USA. Reversible for left hand use.