*Tubeless design with 42mm reflex lens aperture *4 Selectable reticles and 5 brightness settings*Designed to work with Absolute and Lower 1/3 cowitness red dot sights.This reflex sight is assembled manually, so 0.1% of them may not 100% perfect when first time use. It would be highly appreciated if you could send us a message if there is any problem with this sight. (Lens cracked, Can't hold zero etc.) Feyachi Flip Up Rear Front and Iron Sights with Elevation Specification Dimensions: 35mm x 45mm (height) x 30mm, Weight:1.5 oz (Front) 35mm x 40mm (height) x 27mm, Weight:1.8 oz (Rear) Color: Black finish Material: Aluminum Interface: Picatinny / Weaver Rails Feyachi M36 The Feyachi M36 magnifier is a better addition to any user who primarily runs a non-magnified dot or holographic sight on their modern sporting rifle. Designed to work with Absolute and Lower 1/3 cowitness red dot sights, with a fast flip-to-side engagement. The push-button design of the M36 engages and disengages the flip-mount, allowing the magnifier to lock in place. Its all-steel mount made sure this thing was rugged. Positions the M36 at 37 mm from the base surface to the center of the optic. This puts the dot height at a center (absolute) sight picture when co-witnessed with standard iron sights.