Máy đo tốc độ vòng quay Handheld Tachometer with an LED Display (Acquest SKS Coporation) Shimpo DT-107A

Capable of measuring low speed from 0.1 to 25,000 rpm without changing the range setting. Equipped with an LED display that is clearly visible even in dark environments. Available functions include: a memory function that stores maximum, minimum, and last-measured values plus 10 other measurements; and a unit conversion function that can display values in various units such as rpm, ft, in, mil, and m. Power is provided by two AA alkaline batteries.