This well-designed PSSC-type timer is easy to use and accurate. It plugs directly into any 110 V outlet. The timer places a carbon dot on moving ticker tape paper (included) at precisely every 1/60 of a second. By measuring and comparing the space between dots, you can demonstrate velocity, acceleration and friction. The hardwood body is heavy enough to work without clamps, although holes for attaching to a support rod are included. Also featured are shielded electronic connections, adjustable tuning nut and brackets. Includes carbon discs (12) and ticker paper (100').