The GR series 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 and 2 IIB+H2, Class II Groups EFG, Class III, Type 4 and 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 in, 3-1/2 in, 4 in or 4-1/2 in round or rectangular meters such as ammeters and voltmeters.