Image Item No. Description By  4185  Technic Wedge Belt Wheel (Pulley) Catalog: Parts: Wheel 6  55982  Wheel 18mm D. x 14mm with Axle Hole, Fake Bolts and Shallow Spokes Catalog: Parts: Wheel 1  55981  Wheel 18mm D. x 14mm with Pin Hole, Fake Bolts and Shallow Spokes Catalog: Parts: Wheel 1  56145  Wheel 30.4mm D. x 20mm with No Pin Holes and Reinforced Rim Catalog: Parts: Wheel 1  56904  Wheel 30mm D. x 14mm Catalog: Parts: Wheel 2