X-Sense Wireless Interconnected Battery Powered Smoke Detector Fire Alarm with Over 820 ft Transmission Range, SD19-W, Pack of 6Brand: X Sense Color: White Features: Detection Anywhere: Features wireless interconnection so that if one alarm is triggered, they all go off, and they stay connected using radio frequency with a transmission range over 820 ft (250 m) in the open air Ready to Use: The multi pack detectors have already been connected for instant use, and you can connect up to 24 Link+ wireless alarms at a time Customizable Wireless Network: For a customized network,