The Kidde SLED177i (formerly SL177i) is a 120 VAC wire in unit that provides a visual warning when part of an interconnected system. This unit can be directly interconnected with Kidde smoke alarms, heat alarms and carbon monoxide alarms (a maximum of 24 devices of which 18 can by initiating). When triggered by a smoke alarm or heat alarm, it will produce a steady flash warning. When triggered by a carbon monoxide alarm it will produce an intermittent flash warning. SLED177i has a 10 years limited warranty and is UL listed. ATTENTION! the model SLED177i led strobe light is designed to notify hearing impaired individuals of impending danger, it has no detection means and must be used in conjunction with operating interconnected smoke, heat or carbon monoxide alarms.