I've used them to attach lanyards that I made myself. They work well & they are detachable. Also, as someone else suggested in a different thread, you can remove the nylon string & weave it into your lanyard directly.
I prefer using a split ring. The Cabela's #3 split rings have 0.205" ID and 0.033" wire diameter. They fit good and stand up away from the body. If you want the ring to lay down find something with a smaller wire diameter.