Capable of carrying big payloads (bricks!) these dynamic carts will be just as their name implies-dynamic! When collision variables are magnified to the size of bricks, they make an impression on students! Each car is supplied with one lightweight and one heavyweight steel band as well as rubber bumpers. The hand screw posts make for easy exchange of bumpers without the use of tools. You'll get years of crashes with these rugged heavy gauge aluminum carts. Each cart measures 7.6 x 25 cm and comes complete with instructions and experiments.