Only Compatible with newer magazines with the rectangular retaining peg This is an alternative base plate for the Sig Sauer P320 (Full size, Carry, Compact, Subcompact, X5, and X-Carry) that adds 1-2 extra rounds depending on caliber This is designed to work with a flared magwell I created for the X-series grip modules due to the OEM extending too far on either side preventing the use of a magwell. Although not tested these baseplates are likely compatible with the OEM flared magwell. For the most strength print the baseplate on it's rear so that the laye are not parallel to the lip on the magazine body Flared Magwell: Baseplate