NARVA This non audible unit operates at 12 or 24 volts and provides a continuous alternating flash rated at 17 amps per circuit or 8 x 21 watt globes. Solid state electronics are sealed in an epoxy compound which readily dissipates heat from the rugged die-cast aluminium housing. The Alternating UltraFlash is short circuit overload protected with a self resetting feature and can operate within a temperature range of -40 to +82 Celsius