Custom made A1 BUIS sight purchased from AR15 group buy last year. CNC milled from aluminum and anodised. I duracoated this flat black. Locking bolt does not go across rails on receiver and there is a space between bottom of sight and top of some receivers. This upset some of those who purchased these in the group buy. I have two of these and on the one I use I cut a piece of inner tube rubber and epoxied it to bottom of sight. My sight looks good and is solid. For sale is sight only. Not receiver or sight parts. This is a neat custom made sight.