This is an exceptional rare, all original, excellent condition WWII "MG81Z" machine gun produced by the Mauser (byf) factory. These are WWII machine gun rig that it s estimated that there are only a handful of MG81Zs in the US today with most in private museums. These two machine guns are fully functional and fully transferable class III machine guns. The MG81 series of medium machine gun was originally designed by the Mauser factory in 1938 as a single barreled aircraft machine gun, under contract for the German Luftwaffe. These single barreled machine guns were employed in various firing positions in German bombers and fighters, and started replacing the earlier MG15 and MG17 in Luftwaffe aircraft in 1940. Later in WWII they were employed in a ground mounted fashion using a large adjustable tripod, as in this case. This weapon is an air-cooled, recoil operated belt feed machine that could use the standard 7.92mm cartridge, however were really intended to use a special "V-Patrone" cartridge that had a higher muzzle velocity. The basic receiver and feed tray mechanism is very similar to the German MG42 series of machine gun. However since these were intended to fit in confined areas inside aircraft they are sized smaller and lighter and have no buttstock assembly. Instead they have a stamped steel, "D" type loop cocking handle located on the rear of the receiver which is attached to a steel cable that is attached to the bolt mechanism on the underside of the receiver. These loops are intended to cock and load the first round in the gun. This specific model the MG81 "Z" version designates it as being a dual mounted (two machine guns) bolted together, with single trigger mechanism located directly in between the weapons. The concept being that by bolting two machine guns together, would make them more effective, by having an increased volume of fire power, combined with an extremely high rate of fire, estimated at "3200/min" would make them a deadly weapon for aircraft use. Obviously this mounting configuration created various technical and functional problems in the area of feeding and ejecting spent cartridges. Typically machine guns feed from the left or right side and eject the spent cartridges out of the opposite side. To overcome this the Germans designed these machine guns to eject the spent cases downward through a metal hopper located on the bottom of the machine guns, and then the designating links were feed through the two metal shoots mounted on top of the machine guns that also directed them down through the metal hopper. The two machine guns have an excellent late war gray/green phosphate finish overall. The top cover are marked "MG81/54301/L" and "MG81/53402/R" for left and right side MG respectively) over "byf" the secret wartime code assigned to the Mauser factory. The breech end of the barrels over the chamber areas is marked 54301/54302 with "n.A 43" behind the serial numbers, probably indicating the year of manufacture. It has the original anti-aircraft sight assembly mounted on top between the two barrels fixed to the yoke assembly and the front portion has the perforated barrel jackets with barrel recoil assist/flashider mechanism on the end of each barrel. Several of the various parts and/or assemblies are stamped with the late war "Luftwaffe Eagle 2" acceptance proof. It is complete with an original tripod that is adjustable for height, three starter tabs for the belts, with a box of ammunition links and a spare flexible spent cartridge shout with a canvas bag on the bottom. NOTE: This is a fully transferable NFA Class III Firearm currently on a Form 3. You are required to check your state and/or local laws as to whether or not you may own this. This weapon can be transferred to a Class III dealer at no charge. Buyer pays all other transfer fees and stamps.