I bought these security locks to have peace of mind while playing.
I had to do some minor DIY adaptations to install them on my Squier PJ bass: one of them went in just fine, but the one on the top horn was not gripping in the wood as the screws are thinner than the stock ones (and the stock ones don't fit in the security locks). The good ol' trick of toothpick + glue fixed it.
Now, the major issue is on the part that goes on the strap and if you have thick strap, you might be in trouble. I have the betty strap from Mono, and it's just too thick for the locks. When you put the washer, the thread of the bolt is just too short for the nut and you can't tighten it. I somehow managed to get one in place (bolt+washer+nut) but for the life of me I couldn't do it for the other one. I tried to replace the washers with slightly thinner ones, no success. I gave up on it and I directly tightened the nut on the bolt without the washer. So far so good, seems solid and doesn't look like it's getting loose after some months of usage.
tl;dr: Overall I think they do what they are supposed to and they feel secure - for that price it's a no brainer. Overall I would still recommend them. Just watch out if you have a thick strap as you might not be able to tighten the nut using the washer.