Edwards Signaling 860 Series xenon beacons with horns are bright, low current, high decibel, combination signals designed for use where a distinctive visual or audible signal is required. The housing is made of gray, engineered thermoplastic. The strobe and horn can be operated independently. The 867STR (indoor) and 868STR (outdoor) Series can be surface mounted on the supplied surface box. The 869STR and 869DSTR Series beacons can be flush mounted. They are designed to mount in a standard 4" (102mm) square electrical box with extension ring (total min. depth of 3" (75mm) not supplied.) The 869DSTR Series is Diode Polarized for use in electrically supervised circuits.