Accuform scs603 decibel meter sign, caution ear protection may be required, 20 x 12 x 1 specifications: decibel meter sign continuously measure and display the sound level to alert workers of the potential need for hearing protection lightweight, durable aluminum construction with frameless visual edge design to capture the attention three-digit, bright red led display with 1 1/2 numbers viewable from 75 ft. Away meter measures from 30 to 130 db with accuracy to within +/-.5 db requires no additional calibration or settings operates on 110/120 vac with 8 ft. Power cord and ac adapter operational range is 32 to 104 f operates in 10 70% relative humidity; though, not recommended for high humidity environments supports osha 29 cfr 1910.95 hearing conservation program requirements