National Time SG-CXSS15Z Category : National Time This alarm is a ceiling mount speaker/strobe. Brand National TimeModel SG-CXSS15ZManufacturer GentexType Alarm (Speaker/Strobe)
Simplex 4904-9139 Category : SimplexI believe that this strobe plate was designed to be used with bells, such as the Simplex 2901-9333.
Simplex 2098-9806 Category : SimplexThere is no difference between this unit and my other Simplex 2098-9806.