The "E" is for "Extreme." The EXPS3 offers true 2-eyes-open shooting and a 7 mm raised base that still allows for iron sight access. It features easy-to-adjust side buttons and an adjustable, locking, quick-detach lever for easy attachment and removal.
EXPS3 was chosen by the U.S. Special Operations Command (USSOCOM) as their primary optic for close-quarter engagements.
It is also the optic of choice for the technologically advanced modern rifle hunter. Its night vision-compatibility makes it a versatile choice for day or night hunting.