AIM Sports Inc AR Low Profile Rear Flip Up Sight MT201 Aluminum 100% Imported Black anodized aircraft grade aluminum. Ball bearing pivot detent Automatically locks into position when raised. Flip-up posi-lock design to guarantee zero A2 style dual aperture 0.65 MOA on M-4 Type rifles. 0.49 MOA on A-4 type rifle Length: 2.5"