A space saver! The conical redwood dart moves in a nearly frictionless arc to collide with the redwood block, enabling students to easily perform quantitative analysis. The dart has a 4 cm nail head and can be suspended from any right angle extension rod. It measures 4.5 cm at its widest point by 20 cm long. The block measures 9 cm wide by 30 cm high. Furnished with eye screws and suspension cord.