These are my favorite strap locks. They are effortless to get on and off, and there's no way these come off by themselves (even if the nut comes loose they'll hold your instrument until you click them off).
They're also very small and sleek and come in different finishes.
However, do keep in mind that you won't be able to use any strap that doesn't have the lock installed (so you can't just borrow someone else's strap).
And there's only one length of screws included (which happens to be slightly short for my Prestige Ibanez). If this screw is too thick or too short, you don't get the option to use your guitar's screw. It holds my guitars just fine, but I would have preferred having 2 different lengths of screw included in a set.
Other than these two gripes, it's a fantastic product.