Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension Red 5. This base pad is specifically designed for the 17rd magazines. It is not compatible on reduced capacity magazines. Specifications for Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension: Manufacturer: Agency Arms Magazine Capacity: 5 Round Caliber: 9mm Luger Gun Make: Glock Gun Model: Glock 22 Glock 17 Features of Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension Sage Dynamics Engraving Dot Matrix Panel for Marking Chrome Silicon Alloy Spring Increases capacity by 5 rounds (9mm) 4 round (.40s&w & .357) Extended Ledge for One-Handed Manipulations Package Contents: Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension What firearm models does the manufacturer say Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension is compatible with? The manufacturer suggests that Agency Arms Glock 17/22 9mm +5 Rounds Pistol Magazine Extension is compatible with Glock 17 Glock 22Agency Arms AGEBP-G17-RONIN: Glock 17/22 9mm +5 Rounds Pistol Magazine Extension Red