Good alternative on a budget
I am a firm believer in strap locks on all guitars, with Schallers being my favourite. That being said, there are times when I run out of the strap pins, and there are some guitars (like my camp guitars) which simply don't warrant a lot of extra investment.
In those cases, the Fender Strap Blocks are a good middle ground. I like them better than the Dunlop plastic rotating ones, as I have had those come apart on me. The Strapblocks fit nice and tight, are easy to install, and cheap enough to cheap a couple of spare sets in your gig bag.
That being said, I don't know that I'd entrust a $1k+ guitar to these things, a more substantial system would be warranted in that case. I also wouldn't try any guitar spins with these as I don't think they'd hold, then again, if guitar spins is your thing, I guess whatever happens happens.
ConsDon't think they'd hold up to too much abuse.