Designed to measure the speed and acceleration of a moving body with precision and simplification of operations. The striker oscillations are in direct synchronization with the input AC frequency, which eliminates the need to calibrate the timer in correlating input voltage to rotational motor speed. The unique, single-body construction of high-impact plastic provides both shielding for safety and structural strength for classroom use. Operates on 110-V AC and is equipped with an extra-long cord with a 3-prong, grounded plug and off/on switch. Includes 24 carbon discs, roll of recording tape ( 1/2" W × 315 ft L), and instructions.