3 Star CW10S #10 Solid Copper Ground Wire
25 feet of #10 Solid Copper wire as used for common grounding applications involving Low-Voltage Communications installations like Cable TV, TV Antenna, Satellite TV and Wireless Internet. Priced and sold by the foot in continuous roll (25 ft. per unit ordered).
This taken from the FCC:
Antenna Tower Lighting and Marking Requirements
Antenna Tower Lighting and Marking Links