With the Schaller S-Locks presents Schaller the next generation of the famous Security Locks . Introduced in 1981, the guitar strap buckle system now features an extended 6mm screw axis for easy attachment to thick leather straps, while the new Lock-Wheel can be tightened and locked in place with a clamping screw. In addition, the specially turned 4mm thread of the strap pins ensures a secure hold in most common instruments.

This was easy to install and is a step above the other strap locks I bought.
You will however need the following tools in addition to your purchase:
Allen keys.
Screwdriver with a tiny flat head. (used for fixing spectacles?)
The threaded shaft has ample length to go through even a thick guitar strap end.
Worked beautifully and installed it on my more expensive guitar.