Upgrade traditional metal or wooden carts to a more modern pair that runs longer and straighter, and resists damage and corrosion. The 1-piece, heavy-duty, plastic body mounted on a set of 3 low-friction, nylon wheels maintains a straight path. Access and activate the top-mounted trigger knob for the spring-loaded plunger. Use included Velcro® pads on the back of the cart to explore inelastic collisions. Sold as a pair, the stackable carts weigh 1.5 lb each. Includes instructions.