The NSI G-20 Bronze Ground Clamp with Wire Adapters grips on pipes between 1/2" to 1" in diameter and features a special pressure bar which grips wiring and lessens the chances of grounding conductor being pulled out. The zinc-plated steel screws and bronze clamp body are made of economical, high-quality metals that provide durable performance in a range of applications. Use this clamp with wire adapters for connecting unarmored 4, 6, or 8 STR ground wire to water pipe for grounding. UL Listed 467 for Grounding and Bonding. Stock products you can rely on—stock NSI.