Schaller Security S-Locks Pin Set M N

Compatible with chapman straplocks in my case and that was the reason I got it.
The head of one pin's allen screw was not great (the allen tool couldn't fit perfectly), but I was able to tighten it enough to be safe in my guitar, so I didn't have to send it back. The other screw was great though.

Say that you have a strap, or a couple of straps, which you swap between guitars. Straps and guitars - they’ve all got strap lock mechanisms already.

You buy another guitar.
You’ve already got the lock mechanism on the strap, and you don’t want to buy a whole other set of strap locks for your new guitar, with a spare part hanging around.

These are the exact thing you need.

All my guitars have S Lock from Schaller. Great products, decent prince; Just works for me...