CMMG Magazine Mk4/AR15 5.7X28mm 10 Round. 7 AR Conversion Magazines feature a number of improvements. From the new stylized texture grip and "5.7x28mm" engraving on the sides to the upgraded feed lips these magazines are built to exceed your expectations. 5.7 AR Conversion Mags are available in 10 or 32 round capacity and are designed to work with CMMG 5.7x28 Radial Delayed Blowback Uppers and Mk4/Mil-Spec AR15 lower receivers. Specifications for CMMG Mk4/Ar15 5.7X28mm 10RD Magazine: Manufacturer: CMMG Color: Black Magazine Capacity: 10 Round Caliber: 5.7x28mm Gun Make: CMMG Gun Model: CMMG Mk4 AR-15 Quantity: 1 Package Contents: CMMG Mk4/Ar15 5.7X28mm 10RD Magazine What firearm models does the manufacturer say CMMG Mk4/Ar15 5.7X28mm 10RD Magazine is compatible with? The manufacturer says that CMMG Mk4/Ar15 5.7X28mm 10RD Magazine is compatible with AR-15 CMMG Mk4CMMG 54AFC44: Magazine Mk4/AR15 5.7X28mm 10 Round