This is a ProMag End Plate, model PM140B.
This single point sling attachment replaces the collapsible (4 or 6) position butt stock retaining plate. Can be assembled as either a left or right handed attachment. The sling attachment plate allows the use of a single point sling to be hooked into the provided loop" allowing the weapon to be worn on either the right or left side. The plate also allows the standard sling to be attached to the front sling swivel without affecting sling length when the stock is collapsed. It is constructed of carbon steel with a black-oxide finish.
Features:
Single point sling attachment plate
Assembled as either a left or right handed attachment
Allows the weapon to be worn on the left or right side
