This key chain has Union Pacific Challenger 3985 on it. It is the largest and most powerful operating steam engine in the USA today. It is a 4-6-6-4 built in 1943 by the American Locomotive Co. It resides in the UP round house in Cheyenne, WY when it is not out on special runs. This key chain has the same image on both sides and is 2.25 x 2.25" not including the ring.