These are the only extensions for the XD9 and XD40 that have locking plates to keep them from popping off your magazines when your magazine hits the ground. Our testing has found that you can easily add four extra rounds to the 16 round 9MM XD magazine and three extra rounds to the the XD40SW 12 rounds magazine.
Glass Filled Nylon Magazine Extension
Hardened Steel Locking Plate
Extra Power Spring
NOT FOR USE WITH XD(M) AND XD-S (SLIM) MAGAZINES
Note: When installed, your magazine will be longer than 140mm, therefore these are not legal for USPSA Limited and L10