This sound calibrator generates a stable acoustic signal at a controlled frequency and amplitude to verify the accuracy of your sound level meter. REED R8090 Offers This sound calibrator generates a stable acoustic signal at a controlled frequency and amplitude to verify the accuracy of your sound level meter. The R8090 is compatible with all 1/2" diameter microphones. Features Generates stable acoustic signal at a controlled frequency and amplitude to verify sound level meter accuracy Accommodates sound meters with 1/2" diameter microphones Simply place calibrator on microphone, turn on and adjust your sound level meter Complies with IEC 942 Class 2 Included Sound Level Calibrator Battery