The Taylor Freelance +5 magazine for the Glock 9mm Luger/ 40 S&W pistol is constructed of solid brass with a natural brass finish. This magazine extension will increase the capacity of your factory magazine by 5 rounds in 9mm and 4 rounds in 40 S&W with a potential of 1 more round per caliber depending on the magazine tolerance. The length of the magazine with the extension will not exceed the IPSC 140mm length rule when used on Glock 17 or 22 magazines. The extension works with the stock magazine follower and includes an ISMI extra power spring for reliable operation. The added weight of the brass helps to reduce recoil by adding non-reciprocating mass to the pistol and helps empty magazines drop free. 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.