For calibration of all Sper Scientific digital sound meters or any sound level meter with 1” or ½” microphone Conforms to ANSI S1.4-1984 and IEC942 1988 Class 2 standards for acoustical calibrators. Simply place the calibrator on to the digital sound meter’s microphone, turn on the calibrator, and adjust the decibel meter’s reading to either 94 or 114 dB. Operates at a frequency of 1KHz ±4% and with an accuracy of ±0.5 dB. Built in battery check. Easily portable for field use, it comes with a carrying case, adaptors for 1/2” and 1” microphones, instructions and a 9 volt battery. Dimensions: 5” x 1⅞” (127 x 48 mm) Weight: 8.4 oz (238 g).