Rigid Conduit Union, Type Female/Female, Material Zinc Electroplate/Chromate/Epoxy Powder Coat Malleable Iron, Trade Size 4 Inch, Diameter 6-7/16 Inch, Length 3-1/2 Inch, Approval UL 886, CSA C22.2, Applicable Standard NEC 500 to 503/505, Application Hazardous Location, Constructional Feature Explosion-Proof, Dust Ignitionproof, Enclosure Class I Div 1 2 Groups B C D, Class I Zone 1 2, Groups IIA IIB, Class II Div 1 2 Groups E F G, Class III