This set includes sprocket and idler wheel parts. The set includes track parts plus 2 types of sprocket, and lets you power multiple tracks from one shaft. Sprockets and idler wheels are the same diameter for convenience. • 32mm Diameter Sprockets (closed hole) x2 • 32mm Diameter Sprockets (hole bored through) x2 • 32mm Diameter Idler Wheels x3 • Wheel parts are molded in Orange. • 3 different lengths of Metallic Gray elastomer track (30-link x2, 10-link x4, 8-link x4) are included. Use them to get the perfect size for your model. • Two 3x100mm hex shafts and one 3x100mm standard shaft are included.