Set of two dynamics cars constructed of heavy-gauge aluminum with ball bearing wheels to withstand the most severe classroom use. Each car will hold several bricks or support a load of over 90.0 kg (200 lbs.). Two sizes of spring steel and rubber bumpers permit various momentum experiments in elastic and inelastic collisions. Dimensions (exclusive of bumpers and wheels): 7-1/2 cm x 25 cm (3 in. x 10 in.). Instruction guide included.