Pocket Tach 99 is a digital, battery-powered portable non-contact optical tachometer (red LED), which operates up to 36 inches from a reflective tape target using an LED light source. The ergonomic design allows safe, direct line-of-sight viewing of both the rotating target and the display at the same time, while providing a no-slip rubber surface for single hand operation. Pocket Tach 99 in the value-leader of the world-class Pocket Tach Series from Monarch. Operating Range: 2 inches to 36 inches, ±30° Memory: Maximum, Minimum and Last Power: (2) "AA" 1.5 VDC batteries (20 hours) Environmental: 5° to 40°C (0° to 100°F) 80% RH up to 31°C (88°F) Dimensions: 6.92 "H x 2.4"W x 1.6"D Weight: 7 oz. (210 g) Standards: IEC1010-1