Spec Grade Insulated Grounding Bushing, Threaded 

For Threaded Rigid Metal Conduit and IMC.
Types BLG, HBLG, ABLG, RBLG. Copper Plus™ Lay-In-Lug™.

These O-Z/Gedney specification grade insulated bushings provide a grounding lug to allow for grounding of conduit through the insulated bushing. They help protect insulated conductors from abrasion during pulling or due to mechanical vibration, and provide a voltage gradient between the live conductors and ground at the point where conductor insulation is subjected to electrical and mechanical stress.