Decent backup sights, fair price - Trinity Force AR15 Flip Up Iron Sight

There's not much to say about such a simple product. The sights don't lock in either the up or down positions, being held by spring detents only, but they're intended for use when your optics or electronics fail, not all the time. The rear has the usual large and small apertures, and the front sight post is standard and replaceable with aftermarket posts to the user's preference.