The MPA RAT Dovetail Adapter Plate is used on our RAT System (Rapid Adjustment Technology) and attaches the the spigot mount on the BA Chassis System.
This allows the shooter to run the RAT System and all the accessories on both the chassis body and the spigot mount. This will also be needed to run the Magnetospeed Speed Adapter on our chassis.
Simply remove the existing Picatinny rail from your spigot mount and attach the RAT Dovetail Adapter plate. Very simple.