Our extended base pads are legal for USPSA Limited and Open competitions. Attached to the factory magazines they extend the magazine to 141.25mm length (5.56"). These base pads are best matched with Grams Follower and Spring Kit which additionally increases the capacity. In fact, we only run our magazines in a combination with our base pads and Grams spring kits.
For 9 mm / 38 super you will increase from 17 rounds to 24 rounds (requires Grams Kit)