Killark GRB-275L - Compact rectangular enclosures with threaded lens covers, provides view of the interior. High strength, lighter weight, corrosion resistant copper free cast aluminum construction and tempered soda lime glass, cemented in place. Cover o-ring, Nitrile (BUNA-N) material, supplied standard supplied standard for a Type 4X rating. Cast mounting lugs are standard on all boxes. Internal ground screw supplied on all boxes. Electrostatically applied gray powder epoxy/polyester finish on exterior of box and cover. Mounting pans are available. Conduit and device openings factory or field installed. The GR meter enclosures are rectangular boxes with a window screw covers are for use in locations that are hazardous, corrosive, wet, hose down, dust, dirty, under both sever hot and cold ambient conditions. The GR meter enclosures are UL / CSA certified for Class I Groups BCD, Class I Zone 1 & 2 IIB+H2, Class II Groups EFG, Class III, Type 4 & 4X. See factory for ATEX, IEC Ex, Ex d IIB+H2 Ex tD A21 IP66 when ordered with suffix “CEN”. The GR meter enclosures are made of cast copper-free aluminum (less than 4/10 of 1%, supplied standard with a Nitrile (BUNA-N) O-Ring, cast on mounting lugs. The boxes are supplied with meter mounting pans for 3”, 3-12”, 4” or 4-1/2” round or rectangular meters such as ammeters and voltmeters. Supplied with two ¾ NPT conduit openings. Other sizes and quantities are available.