The MALLORY SONALERT part PK-21N30PQ is an audio indicator designed for various applications. It is a piezo type indicator that operates with a voltage range of 1.5VDC to 30VDC, drawing a current of 12mA at 12VDC. With a sound output of 80dBA, it emits a loud and attention-grabbing noise within the frequency range of 2500Hz to 3500Hz. This flange mount indicator comes with convenient wire leads for easy installation. The PK-21N30PQ is available for purchase in bulk quantities.