The GEMTECH SAR57 suppressor in 5.7x28 is for use with the 5-7 Center AR15 uppers. Similar to their SFN-57 pistol suppressor, it is slightly longer, ending in our aggressively-textured rear mount, which allows the suppressor to fit under, but slightly stick forward of the rail system so it may be grabbed to remove and install. This durable and featherweight unit may also be used on .22lr, .22 Magnum, 5mm Remington, .17HMR, and other lesser calibers.