Spectra Precision Laser LL300N Automatic Self-leveling Level w/HL450 Receiver, Alkaline Batteries Basic LL300N package includes HL450 Reciver, rod clamp, 4 "D" Alkaline batteries and carrying case. Meets IP66 Water and Dust Resistant standards Laser Accuracy of + or -3/32 in at 100ft (+ or - 2.2 mm at 30m). Operating Range: 1650 ft (500m) diameter. Self Leveling Range: + or - 5 degree Drop Height on Concrete Performance: 3ft (1m) Fully automatic electronic Self-leveling( with HI Alert) for fast & accurate setups and a 5 year warranty. Class 2 Laser and &lt;3.4mW (less than 3.4 Milliwatts)