More info
1kHz Professional Calibrator for 0.5inch or 1.0inch Microphones
Features:
    Calibrates and verifies Sound Level Meter operation
    LED indicator lights up when power is on
    Level position to select 94dB or 114dB
    For use on Sound Level Meters with 0.5inch or 1.0inch microphones
    Durable die-cast, aluminum housing
    1kHz sine wave at 94dB/114dB is generated to an accuracy of 5% (frequency) and ±0.8dB