Install your P320/P250 firing control unit into this Grip Module Assembly to convert to a P320 or P250 compact chambered in 9mm Luger, .357 SIG, .40 S&W with your selected grip size. Requires the 9mm Luger, .357 SIG and .40 S&W slide and barrel. Designed to function with compact and sub-compact slide. Attention: Not designed for the full-size P320. Will not cover the full-size dust cover leaving the recoil spring and guiderod exposed. 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.