please help me pick out a strap-on for pegging my man.

after reading lots of interesting posts on reddit, we're both excited about pegging. after shopping around online (he refuses to go into a brick & mortar store) we're more confused than ever. we've already bought one that was a complete disappointment because it wouldn't stay in place without me holding it, which is the whole purpose of a strap-on. so seasoned r/sex community, help!