45 Degree offset folding Rear sight perfect for AR15 shooters looking for offset iron sights. Fits onto receiver height Weaver, Picatinny, MIL-STD 1913 type rails. The A2 Dual Aperature (Large & Small) Rear sight is fully adjustable for windage, also with a Large windage knob. Rear sight folds back flat for a lower profile and will fit under the majority of scopes out in the market. Weight: 2.6 oz.