Stopper Dome Heated for Strobe Only NEMA 4X - 240 VAC Hazardous Locations helps protect strobe units where temperature or environmental conditions exceed the suggested operation range. That includes, but are not limited to, refrigerators, freezers, meat packaging plants, arctic environments, ocean rigs, slaughterhouses, etc. Three year guarantee against breakage of polycarbonate in normal use (one year on electro mechanical and electronic components).