1. Easy to operate. 2. Long life battery. 3. Illumination of display. laser distance meter PD 54Brand: RUIDE Model: PD23, PD54, PD56, PD58 ... measurement Continuous, Pythagorean Surface area, volume measurement Addition / grand total √ Battery life, Type AAA, 2×1.5V Up to 5000 measurements ... °C (storage) 0°C to 40°C(operation) laser distance meter 40m