Sperzel Trim-Lok tuning keys are machined from solid billet aluminum for light weight and held to precise tolerances and quality checks to produce a precision tuning key that eliminates shaft wobble, endplay and minimum backlash. Sperzel Trim-Lok model offers no tying or winding around string posts, greatly improving your tuning capabilities for playing style and enjoyment. Rid yourself of Tuning Torture Syndrome!

Another great feature is these keys are reversable! If you need left-handed, buy a 6 inline, take the key off, push the shaft out, push back in from the opposite side, re-attach the key. If you need a 4 on one side and 2 on the other, buy a 6 inline and switch only 2 keys! Very cool!