Lokstrap System

I've only used them with the traditional Fender-style strap pegs. They work great. Saves me from having to install a full strap locking system on all my guitars. I find that if you have to put these on/off very frequently they can fall apart, as others have said... but they're so cheap! I just bought a pair for every guitar I own. Easy.

I actually bought a set of these in a music shop in Salem. I had previously been using beer bottle caps- ooh, that's another thing: don't use beer caps. They will chew straight through your strap. Anyway, I found a set of these for about twice as much in a store, and I thought they were pretty great. They slip right on, they twist shut, and they stay. Eventually I'm going to get some real locks, but for the budget guitarist (is there any other kind?) they are a perfect choice.

I bought these looking for a strap lock system that was cheap and more importantly, allowed me to keep my guitar original. I thought I would try these and was very pleased. They stay on tight!
My only beefs are that they are a little big and can stand out if you have a lighter colored strap. Luckily I use black straps. It can also be a little difficult to get these locks on thicker straps. Actually 'impossible' may be the word if your strap is too thick. The biggest flaw in my opinion is that the locks can become so tight and hard to turn on thicker straps that the strap button actually loosens. The lock will stay on but the button will fall right out, so look out for that.

These strap locks are poor quality. The problem with these strap locks are, once you put your strap on your guitar, you are supposed to put these over your strap and twist it to lock the strap on. Well that will never happen because the thickness of the strap, will not allow you to put the locks on.
So unless your strap is as thin as a couple of sheets of paper, these locks will not even be able to be put on. Even if they were to work, I would not trust them because they come apart. They are made of two pieces of plastic that snap together so they can spin and supposedly lock. When the two pieces come apart it defeats the whole purpose. Don't wast your money, I'm going to return mine.

I like the price. You can get four or five and keep them in your case, your pocket or leave it on the guitar when your not using the strap. They won't scratch or nick your finish like the ones that stay attached to strap. Just make sure to turn it to lock every time you attach the strap.

Inexpensive, effective and best of all no mods to guitars.

Highly recommended.

they do what they say. Especially if you have a classic you don't want to put strap locks on. Like Ben said, a bit of tape on it can really make them not come loose.

These are ok. Sometimes they don't fit over the end pins, especially on my acoustics. They also can pop open if pried hard enough. They are definitely better than nothing, but if you have the money, go for the real strap locks.

They certainly serve the purpose and are well worth the price, but they can sometimes wiggle themselves open and off.
A small piece of electrical tape over the edge can discreetly hold the two parts together very well.