Appleton, Aluminum Die Cast, Watertight Hubs, Furnished with Lug for Grounding Conductor. Insulated and Gasketed, Unique profile permits easy wrenching. Smooth, accurately tapped threads facilitate installation. Corrosion resistant. NEMA Types: 2,3,3R,4,4X,12, 13. Used to connect rigid metal conduit or IMC to a threqadless opening in an enclosure. UL Standard: 514B, UL Listed: E14814, E24264. E11853, CSA Standard: C22.2 No. 18.3. CSA Certified: 065178, NEMA: FB-1, Trade Size 4.0 IN