System Sensor SR SpectrAlert Wall-Mt Selectable Strobe 12/24V, Red The SpectrAlert Advance SR is a red strobe selectable strobe settings of 15, 15/75, 30, 75, 95, 110 and 115 cd. 10 to 93% non-condensing 8 to 17.5 V (12V nominal) or 16 to 33 V (24 nominal) Regulated 12DC/FWR or regulated 24DC/FWR