Channel Master CM 3080 is used to secure a TV antenna mast to a chimney. Two brackets are included to anchor the mast at two different points, as far apart as the chimney will allow. The CM 3080s brackets will accommodate a TV antenna masts with an outer diameter up to 1-1/2 inches. The center of the TV antenna mast is held 3.8" from the chimney. Two 12' metal straps are included.