Can be used as primary or back-up sight; Ergonomic angel-wing-shaped shroud helps center the image with any front sight; Dual apertures are 3mm for longer eye relief mounting, low light, and faster target acquisition; and 1. 5mm for shorter eye relief mounting and greater accuracy; each is instantly selectable to match conditions; Low folded profile is smooth and inconspicuous, and will not snag on gear, webbing, or brush; Instant spring-locked deployment mechanism will not slip, break or deform; No tools needed for easy, rapid windage adjustments, with positive detent locking; Made of extremely durable high-grade polymer and metal