Whether running them as your primary aiming system or relying on them as a back-up in case your main optic goes down, the Geissele Folding Sights will give you the performance you need and expect from a product designed and manufactured from the ground up in our facility located in North Wales, PA. The Geissele Folding Sights are made from 6061-T6 aluminum and are Type 3 hard coat anodized to ensure extreme durability. For optimal aiming precision, our sights can be adjusted at ½” increments at 100 yards. The adjustments for the front and rear sights are captive to ensure that once sighted-in, there won’t be any adjustments not intended by the user. There are no buttons or mechanisms to accidentally bump that will activate or fold down your sights when you least expect it, simply move them up to lock into position, or apply sideward pressure to the vertical tower to lock them down. The peep aperture is .072” and the front post measures .080”. These sights are accurate enough for precision use during competition and rugged enough for duty and personal defense use.