One-piece plastic molded car can be used with an inclined plane, weights, and pulleys (all not included) to study relationship between energy and work Plastic molded wheels with sleeve bearings absorb friction and reduce vibration Car has a 2.3"L x 2.2"W x 0.9"D cavity for placing additional weights Removable metal thumbscrew for attaching and securing cords Overall dimensions: 5.5"L x 2.3"W x 1.4"H; Weight: 2.2oz The Hall's Car can be used with an inclined plane, weights, and pulleys (all not included) to study relationship between energy and work. It features a molded one-piece body with a central well to hold additional masses. The molded wheels have sleeve bearings for absorbing friction and reducing vibration. A removable metal thumscrew at one end can be used to secure a string, cord, or other item to the car. Specifications: Overall dimensions: 5.5"L x 2.3"W x 1.4"H Depression size: 2.3"L x 2.2"W x 0.9"H Weight: 2.2oz