Schaller® Sure Claw - Adjustable Spring Tensioner
This is the Schaller 377 Sure Claw spring tensioner. It allows you to adjust and maintain your tremolo bridge's spring tension without removing your guitar's back cover plate.
Installation
Screw the Schaller Sure Claw into the guitar body in place of the spring claw, then re-attach the springs. You can then adjust the spring tension as you want it through a small hole in the cover plate (please drill this yourself) without having to take the cover off every time.
A spike for center-punching the cover is included as an accessory.
Simply place this spike in the Allen socket on the adjustment unit, then put the cover into place so that it is marked by the spike. This shows you exactly where the cover needs to be drilled, which means you can then make adjustments without having to remove the cover, simply by inserting the Allen wrench through the hole.
For grounding run a ground cable from the bridge to the Sure Claw. Strip the isolation and fan out the braiding. Now place the braiding between the wood and the Sure Claw base plate and tighten the two Sure Claw fixation screws firmly. This will ensure a permanent and reliable ground connection.