We built the NSI GRC-38 Standard Duty Silicon Bronze Grounding Rod Clamp for demanding applications including direct burial, where the simple mechanical design and reliable clamping power of the screw outperform other options. The GRC-38 Grounding Rod Clamp fits over grounding rod with a diameter of 3/8" with room to tighten the clamping screw onto a range of 10 AWG solid to 4 AWG stranded conductors. GRC-family clamps with the -SB suffix have a body and screw made from silicon bronze for maximum strength, and the clamp is UL-listed for direct burial in earth or concrete. Stock products you can rely on—stock NSI.