OEM Glock base pad adds +2 rounds to your 9mm mags and +1 round of 40S&W and .357SIG mags. Please note: This kit includes the basepad extension only. You need the Glock magazine extension insert (OEM PN: SP07165) to function properly. Includes: Includes base pad extension (SP07151) only Fits: Glock 17, 17L, 17C, 19, 22, 23, 24, 26, 27, 28, 31, 32, 33, 34, 35, 37, 38, and 39. Does not work on Glock 42 or 43 magazines, or limited 10 round magazines OEM Glock part