The Shield Arms S15 Magazine Extension adds 5 rounds to your S15 magazine. Our unique, easy access floor plate design allows you to quickly access the spring and follower without having to remove the extension from the magazine body. Features Unique easy access floor plate design to service or clean the magazine body without the need to remove the magazine extension from the magazine body. Index cuts on the extension body to increase grip when coming out of a magazine pouch. Machined from billet 6061 aluminum Type 2 anodized Adds 5 rounds to the S15 magazine Comes with a 12 coil plus power spring Fits Shield Arms S15 magazine only Proudly made in the USA Fits most aftermarket flared mag wells