These were manufacturer by us a few decades back. The one piece extrusion body is made from 7071 Aluminum (same material as an AR15 receiver) and then machined to form the picatinny rail.  It includes a 4140 tool steel alignment bar to keep it squared to the receiver as well as the applicable hardware to mount it.  this mount has a slot in the rear and front side so it can be positioned either to the side (as shown on our Browning) or position it to be in line with the barrel if you remove your rear iron sight. Two mounts can also be placed back to back and allow for dual optics. We have two still in the wrapper if you wish to do this, I would snatch them both, as we do not intend to have any more made in the future.