The LDB-2 Ring/Loop Detector monitors an analog phone line for ringing or an in-use condition. A built-in relay can be activated when either of these conditions are detected. This is ideal for monitoring line status or for providing a visual indication of such. Detects ring voltage and loop connect. Screw terminal connections. Wall mountable with foam tape (included) or screws (not included). Auxiliary 12V DC output. Adjustable time-out for relay closure. Two sets of relay contacts provided. Selectable NO (normally open) or NC (normally closed) relay contacts. Made in the USA.