These are deceivingly similar to the old Schaller buttons, and in that sense absolutely spot on. I've given it a good, not very good, because they are compatible with old Schaller strap locks - more so than the new Schaller S-Lock buttons (after they've ruined your guitar) - but have a little bit more play. But they sit tight and - again, unlike the new S-Locks - don't suddenly disconnect your strap from your axe.
Note: There's a theory going around that the S-Locks slip because of the redesigned strap locks, but actually, the old strap lock also slip of the S-Lock buttons more easily.
So if, like me, you're looking for 'proper' buttons to extend your range of instruments to use with the same strap, get these. Aside the little bit of added play, these are the closest you'll get to the original Schaller Straplock buttons.
Curiously, these come with longer screws than if you buy them in a Fender Strap Lock pack, so I was pleasantly surprised. And good too, because the old Schaller screw heads don't fit into the screw hole of the Fenders. Funny how they've made miniscule design changes, just so that they're not 'real' old-style Schaller buttons. But, per se, these are just as good.