With the 461825 Combination Photo Tachometer and Stroboscope, you may measure Tachometer RPM, measure Stroboscopic speed, and analyze motion. Depending on the measuring mode, the display reverses the character direction. Tachometer memory saves the most recent, maximum, and minimum readings for easy recall. Strobe has three flash rate ranges with coarse and fine flash rate settings. The kit includes 4 AA batteries, reflective tape, and a carrying box.