"Flap Latch" is simple strap lock, which made of leather.
Locking mechanism is built on strap end, and it had designed to works with normal strap pin. As same as many of Guitar straps, it's made by leather. And it's weight is only 3g, which is much lighter than Metal made strap lock pin. No noise due to rattling or rubbing of metal parts is also produced.
"Flap Latch" can also uses to Guitar which have heel mounted strap pin.
For example, Gibson ES335, SG...etc. Disengage the fastening string, remove the "flap.And Please re-fasten the "flap" on the back side of the strap.
You do not need to modify your guitar.
"Flap Latch" is differ from metal, rubber, plastics made strap locks, and it fit naturally around a strap pin.
Looking at the pictures you will find that "flap" is lifted a little between the straps and the strap pin. This is because the "flap" is made to be a little longer than the strap end so it becomes like this. when the strap is pulled in the direction of pulling out, "flap" comes under the umbrella of the strap pin, and "Latch " this.
Famous manufacturer's strap lock pin. They are also solidly built, Once you set it up and detach it is one touch. Although it is a convenient product, does not it think that it is too heavy.
Above all, I'm also worried that the position where the strap takes is away from the body of the guitar. The stress that the body receives from the strap pin increases as the position at which the strap is applied is away from the body.
Since "Flap Latch" can use the standard strap pin as it is, it hangs the weight of the guitar in the position of about 3 mm from the body surface.