OCAL™ Double-coated knockout hub made of zinc. Captive sealing ring won't buckle or slip during installation and provides a complete 360° seal, even when conduit is not perpendicular to the enclosure. Hexagonal/splined body and locknut enables fast and easy installation. Insulated throat molded from 105°C rated thermoplastic, UL94V-0 flammability rated. Sharper and deeper teeth provide a more penetrating bite for improved bonding to the enclosure. Nominal 0.04 inch (40 mils) PVC coating bonded to exterior. Pressure-sealing sleeves protect connections. Unique sealing ring and groove design for optimum performance.