Idk all kinds of them, rubber ones and everything else.
14" J&J Ceramic
Viewloader 12v Revy with Xboard
Sometimes a remote
Thats about it
Not really into the push pull with the litttle plastic thing
From my experience, if you have a bad break, you dont want to push it farther back into your barrel. You have to do this because you cant actually run it through, just push pull action. They work a little bit and are definitely handy in the field if you need a quicky. I think you can probably get 'em on clearance for about $6 at wal-mart.
It's alright, it gets the job done when it need to be. Plus your not going to be spending a whole lot so its not a big deal.