42021 is an RCBS primer tool. It uses standard shell holders. The arm is designed to hold a tube of about a hundred primers and feed them one at a time.
I'm trying to find out exactly what these are so I can find prices and sell them. and I'm trying to decide weather to sell the conversion kit or keep it and buy the gun that it goes to. suppose it won't be cheap though. LOL. I have a Swiss range finder and was thinking maybe the thing with the white plates goes with that????? I really appreciate the reply's guys thanks.