Dynamic carts, set of 2

Precision pair of 12"-long, 3-wheel carts with ball bearing wheels. (The cart body is either high-impact plastic or wood and aluminum with either wooden peg or metal post mechanism, depending on availability.) Use these carts for acceleration and velocity studies. Includes a spring release on one cart and elastic tow bands. Carts can be loaded with books, bricks or weights. With study guide.