The Strike Industries Aluminum Extended Magazine Plate for SIG SAUER P320 (9mm) is crafted to seamlessly fit 21, 17, and 15-round SIG SAUER P320 magazines. Offering an additional plus 5 rounds for 9mm, it's machined from sturdy 6061-T6 aluminum to ensure a durable construction. At 1.97oz, the Strike P320 EMP boasts a slim, low drag, no snag design that optimizes its performance. Its dimensions also comply with USPSA rules.