Ed Brown Performance Magazines for GLOCK 9mm pistols are manufactured just like the traditional magazines with a steel line and polymer outer body. Held to the same exacting standards as you have come to expect from all Ed Brown Performance Magazines. Offered in 9mm with a 15 round, 17 round, and the 31 round magazines, to work in the pre-Gen5 Model 17, 19, or the 31 round magazines can work in any 9mm GLOCK as well as AR9mm that accept GLOCK style magazines as well. This replacement magazine will meet or exceed factory magazine performance and carries the same Lifetime Warranty as you expect from Ed Brown. DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.