The KB and KDB drain and breather are installed either the bottom top of an enclosure. When installed in the bottom they act as a gravity fed drain to expel moisture from condensation that can build up in electrical enclosures when installed in the top of an enclosure it acts as a breather allowing air to enter and prevent a vacuum which can cause the drain not to flow properly. They are UL/cCSAus/FM certified for Class I Class I Zone 1 and 2 Class III, Type 4 and 4X. Also, ATEX, IEC Ex, Ex db IP66 with suffix "CEN". Review each part for hazardous rating suitability and notified body. The KB and KDB are offered in aluminum, 300 series stainless steel and 316 stainless steel. Thread sizes 1/4 in to 1/2 in NPT and metric sizes M16 and M20.