Schaller M6 in a 3+3 headstock configuration. Gear ratio 1:16. Price per set of 6 With this tuner the string is locked in the shaft by a handy knurled nut located on the rear of the peg head, resulting in a low overall height. 6-in-line models with two different shaft lengths (staggered). Gear ratio 1:16.
Schaller was the world's first manufacturer who developed the locking tuner and had it patented more than 20 years ago! Works like a traditional machine head, but the string needn't be "wound up" any more. Instead it is inserted into the cam hole with the clamp screw loosened, locked with the clamp screw and can then be tuned at once. This makes changing your strings a lot faster and easier.
Using Schaller back locking machine heads
Now you can tune your strings.