Demonstrate what an air track can, at a fraction of the price. Study momentum and elastic and inelastic collisions with our all-inclusive set. Each car has four ball bearing wheels and a choice of bumpers and holds over 200 pounds (5 bricks). Wide base and low profile mean ease in carrying bulky load. Bumpers screw onto the front of each car without tools. Includes two heavy gauge aluminum cars; two small spring bumpers, light; two small spring bumpers, heavy; one large loop spring bumper; instructions with theory and experiments.