GG&G - New A2 Spring Actuated Buis (Back Up Iron Sight) The New GG&G A2 Spring Actuated BUIS (Back Up Iron Sight) is the latest evolution in GG&G's BUIS product line. Many operators requested that they manufacture an A2 BUIS that would deploy with just a push of a button. Here it is. The unique and proprietary design of the mechanism allows the actuator spring and mechanical components to be captivated and therefore not be open to the environmental elements. The sight not only springs into an on target position with just the push of the actuator button, but it also locks solidly into the upright on target position. No other spring actuated BUIS offers this important feature. Another push of the button and the lock is released allowing you to set the sight into the locked down position. Unlike others in the market place, this can easily be accomplished with just one hand. The sight cannot be folded down without depressing the actuator button located on the left side of the sight base. This totally eliminates the possibility of accidentally lowering the sight. The New GG&G A2 Spring Actuated BUIS provides the operator with an easy-to-install push button operated flip up rear sight. They could have located the actuator botton on either side, but the left side was chosen so that actuation of the sight could easily be accomplished with the off-hand, and not the fire contol hand. The Spring Actuated A2 BUIS can be used as a stand-alone sight or in conjunction with one of their interface rails. It can also be used as a co-witness iron sight with most red dot sighting systems. Weighing in at just over four ounces, this sight features the standard military A2-style double peep aperture which allows for end user known point of impact. The sight has full windage adjustment with standard military windage knob and windage screw. No need to retrain when using this sight. One click of the windage knob provides approximately 0.48 MOA change when mounted on the M16A2E4 rifle and about 0.65 MOA on the M4 carbine. Initial zero is set by adjusting the weapons front sight post. It is low profile so that when in the down position, it will clear most optics. The mount body and sight stem are manufactured from solid billet 6061 T6 aluminum alloy and are Type III hard coat anodized in a non-reflective black mil-spec finish to provide combat durability. All steel components are black manganese phosphated per mil spec. All sight components are standard M16A2 sight components.