Small compact, 3-1/2 in Dia round body enclosures, two single port depths to choose from. Also available in a double port style. Option of 4 threaded lens covers and 4 blank threaded cover in 4 depths. The HK series is for use in locations that are hazardous, corrosive, wet, hose down, dust, dirty, under both sever hot and cold ambient conditions. They are UL/CSA/FM certified for Class I Groups BCD, Class I Zone 1 and 2 IIB+H2, Class II Groups EFG, Class III, Type 4 and 4X. Also ATEX, IEC Ex, Ex db IIC, Ex e IIC, Ex tb IIIC T4, T3 IP66 with suffix C. Supplied with 3/4 in NPT conduit openings, additional openings are available. HK series is made of cast copper free aluminum (less than 4/10 of 1%), supplied standard with a Nitrile (BUNA-N) O-Ring, internal external ground (earth) screws, stainless steel tamper proof locking set screw and electrostatically applied gray powder paint. Internal X pad for mounting instruments or terminals.