Arca Swiss and MPA...

Clamp for what? I'm using the MPA RAT bipod base for the Atlas bipod, so i can have the bipod out on the spigot mount or I can bring it up on the chassis if Im shooting off something real short like the top of a 55 gallon drum. Their RAT barricade stop has also worked well for me.
 
If you have Arcalock the Area 419 is the ticket. For regular Arca the RRA BTC saves you a few bucks. But I have both and they are excellent.