I bought these for my son's Thomann Harley Benton mini-strat and they work a treat.
Having on my son's guitar is a very good test for their ability to fulfill their purpose.
With my son walking around the house equipped with guitar, bashing the doors, cabinets, table etc. the locks show no sign of coming loose or coming off completely. If they can survive this then they can pretty much survive anything.
Would I be happy to put these on my 1000¤ guitars ...... maybe not (but than anyone is asking for trouble putting 5¤ strap locks on expensive guitars), I might go for something a little more substantial, but saying that they are not much different to the more expensive brands.
Once screwed onto the strap and the other part replacing the existing strap buttons with lock together pretty good. I put on another large washer on the strap part to have more grip either side of the strap and this made a much better gripping surface.
For the price, 'you pays your money, you takes your choice'. They are nice strap locks, do what they are supposed to do, but might not put them on the guitars which I would never forgive myself it they ended up on the floor.
All in all nice strap lock.