Greenlee 620K Security and Alarm Kit 200EP inductive amplifier includes adjustable volume control, an LED for visual signal strength indication and powerful speaker for use in noisy environments 620 Alarm Loop Verifier / Tone Generator is designed specifically for the alarm & security industry. Latching feature provides a simple method for identifying intermittent failures and confirming operation of switches at remote locations In latching mode, the #620 tone generator will catch the alarm condition and continue sounding until it is reset. Battery operated, 9V not included