These replace the magazine base plate on the Hellcat and Hellcat Pro (not for 10rnd Pro magazines). This grip extension will not increase the capacity of the magazine and add approximately 3/4" inch additional gripping surface. It also incorporates a texture similar to the frame. This unit replaces the magazine base plate on the Taurus GX4 and GX4 XL. This grip extension will not increase the capacity of the magazine. Adds approximately 3/4" inch additional gripping surface. It also incorporates a texture similar to the frame. ***Will not work on factory 10 round HELLCAT PRO magazines with extended plastic spacers. This product utilizes the patented PearceLock attachment mechanism.(US 10,996,010 B2)