The AC-1 acoustical calibrator supplies three dB levels for noise calibration: 94 dB, 114 dB and 124 dB. Unit is equipped to receive a standard 0.5-inch (1.3 cm) microphone. Adapters are available for four different size microphones. Available as an option with MARK Series Dosimeter Kits, Survey Packs and Travel Packs. Lightweight, easy-to-use, reliable.