Lock-It Cotton Strap BK

Nice simple locking mechanism with no need to replace the strap buttons. If you have a Core PRS, note that it is a little tougher to get this on but it does fit, at least it did for me. One thing to note is that the leather ends extend a little further past the strap holes than a regular strap, so on a guitar like a PRS singlecut where the button is just above the neck, the end of the strap is might rub against the neck. This could be a deal breaker for some. On a strat or tele though, no prob.
Update: I thought I'd try it on my acoustic where the strap button is on the back of the guitar where the neck meets the body. I found that the plastic knob for sliding the locking mechanism may with movement knock on the guitar. So it's something to keep in mind if you plan on using it with your acoustic, I think I'll stick with an old strap for my acoustic. I'm not changing my rating though. I still think it's great, but may be better suited to electrics.