Sperzel 6-In-Line Trim-Lok Reverse Tuners Black 6-In-Line Trim-Lok Reverse Tuners Black Sperzel 6-In-Line Trim-Lok Reverse Tuners are ideal for electric guitars with tremolo arms Precision-machined, Sperzel Trim-Lok Tuners feature sealed lubrication and a rear thumbscrew that locks your strings in place Sperzel 6-In-Line Trim-Lok Reverse Tuners are ideal for electric guitars with tremolo arms Precision-machined, Sperzel Trim-Lok Tuners feature sealed lubrication and a rear thumbscrew that locks your strings in place