The SD Magazine Base Pad Extension from Apex Tactical adds three rounds to your existing magazine's capacity. It is manufactured from aerospace grade 6061-T651 aluminum for durability and type 3 Hard Anodized for longevity. It has a single set screw to keep the magazine extension snuggly in place and allow for ease of disassembly when removed. Dimples on the bottom allow for ease of magazine identification.NoteSmith & Wesson SD & SDVE Series semi-auto pistols (SD9, SD40, SD9VE & SD40VE).