Greenlee 93-20 Specifications: Capacity: Lo - 35 to 80 dB; Hi - 75-120 dB Audible Range: “A” Scale Frequency: 20-20,000 Hz Size: 6-3/8" x 2-1/2" x 1-1/2" (162 x 64 x 38 mm) Batteries: 1 - 9V, included. 93-20 Features: Monitor sound level in factories, airports, hotels, offices, schools; check motors, ventilation equipment and hydraulic systems. Analog meter with rotary selector switch and directional microphone. Noise measurement adapted to dB(A) weighting.