Amprobe-SC-3500-Signal-clamp-for-AT-3500-Amprobe-SC-3500-The-Amprobe-SC-3500-signal-clamp-is-an-optional-accessory-for-the-AT-3500-underground-pipe-&-cable-locator-system-that-will-allow-active-locating-of-buried-cables-up-to-4-inches-in-diameter-BR-Amprobe-Sc-3500-Signal-Clamp-for-At-3500