The 552 is EOTech's most affordable night vision-compatible sight and it partners with most night vision-devices. The 552 is designed to increase your speed to target even after the sun goes down. Features 20 daylight setting. *Note- The XR308 reticle was designed specifically for the military M240 machine gun. It should be used with .308 cal with 150 gr M59 FMJ at roughly 2,800 fps with a 24.8" barrel.