Eotech has done it again by making the best even better. Offering true 2 eyes open shooting, a transversely mounted lithium 123 battery, and 7 mm raised base offering iron sight access, the new Extreme-XPS (EXPS) features easy to adjust side buttons and a single, quick release throw lever for easy attachment and removal. Single transverse 123 battery to reduce sight length. Shortened base only requires at most 2 3/4 inch of rail space compared to the 4 inch N battery sights. Battery cap and latch are eliminated and replaced with a simple O-ring, tethered cap; better sealing is achieved. Battery compartment is now separated from the base to allow it to hover over the delta ring of the rifle. Average battery life at brightness level 12 is roughly 500-600 hours, 3X battery life of N cell sights. Side buttons, NV compatible with a single quick detach throw lever.