This is a copy of the M40A1 optics mount used for the Unertl 10x. It is CNC machined out of bar stock. We offer one that requires clip slotting and a different version that does not. These are not always in stock so contact us to get yours ordered. Price listed below is in the white, they can be parkerized or blued for an additional charge. These are NOT made from castings, they never have been and never will be.