Grounding Bushing, 2", Threaded, Insulated, Malleable Iron2", Insulated Ground Bushing, Threaded, Bushing Material: Malleable Iron, Lug Material: Aluminum. Wire Size: 14 AWG (Solid) 4 AWG (Stranded). For Copper or Aluminum Grounding. Temperature rating 150 C. Insulating liner material is self extinguishing. The plastic liner is tough. It won't chip, crack, swell or shrink. It resists corrosion, chemicals and temperature extremes. Surface friction is so low that wires can be pulled with virtually no abrasion