Two coaster cars equal double the trouble with the Double Doom Roller Coaster Building Set! Build with 891 K'NEX pieces including classic rods, classic connectors, and track that build a model over 3 feet high! With the motorized action, your 2 coaster cars will go on a twisting and turning ride. For more fun, download instructions for a 2nd coaster. Models can be built one at a time. Requires 2 "AA" batteries (not included). Rods and connectors Made in the USA. Ages 9+.