This is an 18th, 19th century reproduction Cross Belt Buckle. The buckle was made from an original buckle. The buckle measures 3" X 2 1/8" and is made of solid brass. The back has two studs used to attach the buckle to the belt. You will need two small washers to go over the studs once the studs are through the leather and then lightly peen the studs to secure the buckle to the belt. The hook is used on the belt for length adjustment. The buckle was used for cross belts to hold your bayonet, cartridge box or sword. The leather used could be white buff, black or natural , my personal opinion on the weight of the leather is about 6 to 7oz. leather. This seems to work best. The front of the buckle is highly polished and the back left natural. The original was made this way.