A magazine grip extension replaces the magazine base plate increasing the total length of the magazine. Increasing the total length of the magazine provides for extra grip length which in turn stimulates superior control and comfort. These units replace the magazine floor plate and internal floor plate on the 9mm (13 round only), 40 S&W, 375 SIG and the 45 GAP. These units will add approximately 1 inch in length and additional capacity.Notes:These extensions will not work with the 10 round 9mm magazines nor the XDM frame.