Sig Sauer P320 X-Series Grip Module, Full Size, 9mm/.40/.357, Medium. Install your P320/P250 firing control unit into this Grip Module Assembly to convert your P320 or P250 carry chambered in 9mm, .357 SIG, .40 S&W to a Large Full -Size X-Series pistol system. Requires the 9mm, .357 SIG and .40 AUTO slide and barrel. This X-Series grip features an extended beavertail and high undercut trigger guard to promote a higher grip along with improved recoil control. Available in black and coyote brown polymer.