This unit replaces the magazine base plate on the M&P 9 SHIELD PLUS and 30 Super Carry. This extension does not alter the capacity of the magazine. It adds approximately 3/4" inch additional gripping surface and incorporates a texture pattern similar to the frame. FOR 10 round 9mm magazines and 13 round 30 SC ONLY. NOT FOR EZ FRAMES. NOT FOR ORIGINAL SHIELD "single stack" FRAMES.