The 7139LS is a 120VAC with 9VDC battery back-up photoelectric smoke alarm designed to give reliable early warning of the presence of smoke where both audible and visual alarms are required. The 7139LS a 9-foot plug-in line cord for ease of installation in any space where a visual alarm is required. Fully insect screened. 120 VAC with 9VDC battery back-up | 90dBA temporal 3 evacuation piezo horn with 3100Hz (nominal) horn frequency | On-site washing program | Nominal 2.5% sensitivity | 3 position test switch | Low or missing battery indicator | 9′ plug-in line cord | 1 year warranty from date of purchase.