Model: The smoke box door, upper boiler part, the tender body, the driving wheels, pilot wheels and trailing truck wheels, the side rods, and drive rods, as well as various separately applied parts are constructed of metal and plated with 24 carat gold. The locomotive has an mfx+ digital decoder and extensive sound functions. It also has controlled high-efficiency propulsion. 6 axles powered, 6 axles powered using side rods. Traction tires. The locomotive has an articulated frame enabling it to negotiate sharp curves. It also has Boxpok driving wheels. The middle driving axles are spring-loaded. The headlight, backup light on the tender, and the number board lights are maintenance-free, warm white LEDs. 2 smoke generators (7226) can be installed in the locomotive; the contacts for them are on constantly. The headlight, backup light on the tender, and the number board lights will work in conventional operation and can be controlled digitally. The cab lighting can be controlled in digital operation. Coupler hooks can be inserted in the pilot on the front of the locomotive. There is a close coupling between the locomotive and tender. Steam lines are mounted to swing out and back with the cylinders. The locomotive has separately applied metal grab irons. There are many separately applied details. Figures of a locomotive engineer and fireman for the engineer's cab are included. This "Big Boy" comes in exclusive packaging with a certificate of authenticity. The locomotive and certificate of authenticity are consecutively numbered. A pair of cotton gloves as well as a booklet about the origin of the model are included. A 24 carat gold plated pickup shoe is included for replacing the factory-installed pickup shoe. Length over the couplers approximately 46.5 cm / 18-5/16". Notes for operating this locomotive: The locomotive can be used on curved track with a radius of 360 mm / 14-3/16" or more, however we recommend larger radii. Due to the overhang of the long boiler, signals, catenary masts, bridge railings, tunnel portals, etc. must be installed for sufficient clearance on curves. The track must be well mounted due to the heavy weight of the locomotive. The locomotive can only be run through a turntable or transfer table. Products bearing "Union Pacific" are made under trademark license from the Union Pacific Railroad Company. Find more Märklin explanation videos on our YouTube Channel Spare parts for our articles can be found here in our spare parts search. This model is being issued in 2026 in a one-time series worldwide of only 1,776 pieces for the 250th anniversary of the independence of the United States of America.