These flats are for the bulged trunnion RPK 74 Bulgarian kits. The flats and rails are made from 4130 and are in the soft annealed condition and need to be heat treated after bending.
The RPK flats don't have magwell dimples, but have different bolt guide rails that make up for it.
You must use a bending die that is made for 1.5mm receiver flats due to the inside dimensions of the RPK being smaller than the normal 1mm flats.
This item is made in the United States and counts as a 922r compliant part.