Serene Central Alert Door Knock Sensor

The Serene Door Knock Sensor alerts you when someone is at the door. Never miss another visitor or package again! Must use with the Serene Central Alert System, does not work alone.

• Detects the vibration on door knocking.
• Can also detect the activation voltage of your doorbell or door chime.
• Battery-life is approximately 10 months.
• Compatible with CA-360, CA-380, CA-PX, CA-CX, CA-Mini, and CA-RX CentralAlert systems.
• The device is compatible with magnetic switch.