Gentex introduces GN-503 Series, combination photoelectric smoke and carbon monoxide alarm designed primarily for applications such as hotels, motels, hospitals, college dormitories and nursing homes. The GN-503 Series utilizes both photoelectric and electrochemical sensing technology to deliver reliable performance wherever smoke and CO detection is required. The product is in compliance with UL 217, UL 2034 NFPA 72 and NFPA 720. The GN-503 Series is a 120VAC hard wired alarm with 9VDC alkaline battery back-up in the event the building power is lost. The GN-503 features Dualink®, which enables interconnectivity with Gentex tandem-capable smoke alarms and push button functionality test.