Unlike other stop-gap solutions such as after-market followers or springs, the DURAMAG .450 Bushmaster is a complete solution designed from the ground up to properly support the round in a magazine that fits into the AR15 magazine well. By creating a proprietary internal bracing system and laser-welding it into a 410 stainless-steel body, DURAMAG is able to control round stack and prevent misalignment when rounds attempt to double stack. DURAMAG's system also ensures the thousandth round feeds just as reliably as the first.Specifications: Caliber: 450 Bushmaster Model: SS Series: Replacement Magazine Color: Black with Black Follower Material: 410 Stainless Steel Capacity: 5rd Firearm Fit: AR-15 Style: Detachable Max Capacity: 5