The GR series rectangular boxes with screw covers are for use in locations that are hazardous, corrosive, wet, hose down, dust, dirty, under both sever hot and cold ambient conditions. Cover options; blank flat, lens and domes. The GRs 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.