Fort Smart Outdoor Mains Powered Siren for Smart Home Alarm System. This mains powered siren adds a layer of additional security to your Smart Alarm system with its incredibly powerful 110 decibel siren and LED light panel to notify neighbours and passers by, of an intruder. It links with the click of a button to the Fort Smart Alarm Hub (sold separately) via radio frequency and can be placed up to 80m (clear line of site) from the hub.