30 Watt 12VDC Siren is weatherproof with a 115db sound level. The loudest that we carry. Simply connects to the relay output of the Optex Receiver. This siren requires a 12V 1 Amp power source (item 60-301) if being used with any alarm receiver which does not have a 12V 1 Amp output. Cone 6"x4" diameter x 8" long.