Korpa 
With this tuner the string is locked in the shaft by a handy knurled nut located on the rear of the peghead, resulting in a low overall height. 6-in-line models with two different shaft lengths (staggered). Gear ratio 1:16.
Available in two housing versions:
Screw mount with 135° lug
Pin lock
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.
Only this patented locking system based on the ball socket principle prevents reliably from string notching and breakage.
The string will not be wound onto the shaft any more. So it will stay in tune extremely well, perfect for non-locking tremolo systems.
With all its benefits the Schaller locking tuner is THE benchmark in the guitar sector!
For thicker headstocks, our locking machine head is also available on request with a shaft length of 21mm instead of 18.5 or 19.5mm (staggered).
All sealed tuners are lubricated with Schaller special grease for lifetime maintenance-free service.
All parts are precision-crafted and surface-finished, the self-locking drive ensures an even, delicate and steady tuning.
All string posts are made of high-grade brass and fitted into the housing with utmost precision, ensuring the best possible tuning accuracy and wear resistance.
Besides the standard combinations (e.g. 6-in-line or 3/3), all tuner sets may also be ordered with any quantity of left and right tuners.
The banjo bolt has a standard length of 13mm; alternatively, it can be supplied with a 12mm or 16mm length as desired (please see under Products/Product help/Guidelines/Machine Heads).
Instructions:
Unscrew the knurled screw on the housing anti-clockwise until the clamping ball comes off.
Now press the strings against the clamping ball. Under pressure, it recedes. You can now put the guitar string through the adjusting axis.
Screw the knurled screw clockwise until it is hand tight. The string is now secured by the clamping ball.
Now you can tune your strings.
