The Extech 407744 is a precision sound level calibrator designed to verify and calibrate 0.5” or 1.0” microphone-equipped sound level meters. It generates a stable 1kHz sine wave at 94dB with ±0.5dB accuracy and less than 2% total harmonic distortion (THD). Housed in a rugged die-cast aluminum body and compliant with IEC 60942:1997 standards, it includes a battery test LED, making it ideal for field technicians, industrial hygienists, and laboratory use.