Install your P320 firing control unit into this Grip Module Assembly to convert to a P320 X-Series Carry chambered in 9mm, .357 SIG, .40AUTO with your selected grip size. Requires the 9mm, .357 SIG and .40AUTO slide and barrel. Please Note - The X-Series Grip Modules will not work with magazines that have "SIG SAUER" on the baseplate. They are compatible with the baseplates that have the SIG Mark on it.