This set of four O-rings is a great choice for your harness needs. They are perfect in every way that I can think of! At this price, you can't pass them up. They will also last a really long time, if not a lifetime.
The most helpful critical review
O o it's Magic!
Not quite for cock ring use unless your man is quite girthy, but honestly a staple for any o-ring compatible strap-on harness.