The Checkline CDT-1000HD Hand-Held Digital Tachometer accurately measures rotational speed (RPM) using a visible beam of light. The CDT-1000HD can be up to 24 inches (60 cm) away from the small piece of reflective tape that is affixed to the rotating element. The Checkline CDT-1000HD's rugged construction, portability and outstanding features make It an ideal choice for maintenance personnel, machine operators or others in a wide variety of machinery and material handling applications.