Flip-up sights deploy with the flick of a finger to provide instant back-up, so you stay in the fight if your optic or laser sight fails. Super-smooth pivot mechanism with sturdy ball-bearing detent locks positively in the raised position and stays locked until you hit the pushbutton release. Sight folds down neatly out of your sight path when not in use. Machined from high-quality 6061 T6 aluminum and hardcoat anodized for increased wear-resistance. Hex wrench included with all models for easy installation. Rear Sights clamp securely to flattop receivers. Flip-style A2 aperture features a small peep opening for long-range daylight shots and a large opening for close-range and low-light work. Same-plane calibration ensures the point of impact will not change when switching from one aperture to the other. Deeply grooved knob provides positive clicks for windage adjustment in .65 MOA increments on rifles and carbines with 16" barrels and .49 MOA on rifles with 20" barrels. MCTAR-SPLP - Low-profile design is less than ½" high when folded, yet provides full windage adjustment like the ERS model. Aperture has .070" and .200" diameter peeps.