The REED R8090 is a compact acoustic calibrator used to field-verify sound level meters before and after noise surveys, generating a steady reference tone at two selectable output levels (94dB and 114dB) at 1kHz. It's built to IEC 60942 Class 2 accuracy (+/-0.5dB) and fits any 1/2 in diameter measurement microphone, running on a single 9V battery. This NIST-traceable version includes the calibrator plus an accredited certificate documenting its output against a known standard, letting technicians prove their calibration chain during audits.