This kit includes Classic Schaller S-locks, with a machine screw specific for McPherson heel button, as well as the Music Nomad Acousti-Loc adapter for the endpin jack.
Since McPhersons are designed with a metal pin inside the heel of the guitar, typical strap lock kits with a wood screw will sheer off when installation is attempted, and can be very problematic.
Only use the provided machine screw in this kit.