I never was able to find that missing strap lock, and the other one is officially almost dead. There is a huge crack in it. They lasted four months, but for the price I'm thinking of getting another set. At a cost of a dollar a month I think [for my situation] they work.
Other strap locks cost upwards of twelve dollars, but need to be insulted on your bass. It's fairly common to drill into your bass to make them work, and that's one step I just don't want to my bass. I've also heard it can be a pain to get the strap on and off [like grab a wrench] when I actually want the strap to come off.
With these simple strap locks it's no problem, they come on and off easily enough and give audible warning when I'm being too rough.