Rigid Conduit Reducer Bushing, Type Flush, Threaded, Large End Trade Size 3-1/2 Inch, Small End Trade Size 2-1/2 Inch, Length 1.38 Inch, Enclosure Class I Div 1 2 Group B C D, Class I Zone 1 2 Group IIA IIB, Class II Div 1 2 Group E F G, Class III, Material Natural Finished Copper Free Aluminum, Approval UL 886, CSA C22.2, Applicable Standard NEC 500 to 503/505, Constructional Feature Explosionproof, Dust Ignitionproof, Used On Rigid Conduit/IMC