THOMAS BOULDER MOUNTAIN SET LC99550F Based on the classic story, "Rusty and the Boulder." Thumper sets Boulder into motion, rolling down the mountain and along the track until it knocks over the deserted building. This 35-piece set includes Boulder, Thumper, Rusty, Oliver, Mountain, arched stone bridge, rail crossing 26 pieces of track, and other trees and signs. Assembled set measures 25" x 30".