I discovered these in the mid 90's when fender included them as OEM equipment on their American Deluxe Series Basses... And I've used them ever since.
They're available in Gold, Chrome, Black, and Black Nickel.
I don't play bass without them! On top of the lock mechanism that they have, they also have a built in cradle that holds the bass, so that your strap doesn't wear... And as an added bonus, they prevent damage to you bass's finish, because once installed, these prevent any strap to body contact.
They come with all of the necessary hardware and they are a precision made part. There're a few copies out there, but they're inferior to these and not worth saving a few bucks.
Personally, I put a dab of crazy glue in the screw hole before screwing these on, and it prevents any backing out or wood wear... have been doing this with my bridges, pick guards, pups, tuning machines, and strap locks for well over 20 years.
One note... if you sell your bass, be sure to remove these strap buttons and reinstall the Oem's, otherwise, when you get a new bass, your strap won't work, and you'll have to buy another set... which ultimately leads to you having an excess of the part that goes on the strap....
Schaller Strap Locks