This is a USMC KAC Back Up Iron Sight (BUIS). It is a genuine piece of militaria made by Knights Armament in the United States. The brand is well-known for producing quality items, making it a great addition to firearm or collection. The engravings are marked for United States Marine Corps. It is an original piece, not a reproduction. Gunsmith inspected and certified. Tested in combat and ready for more use!