$63.99 National Hardware 1/2 in. Zinc-Plated Wire Cable Clamp-3230BC 1/2 WR CBL CLMP - The Home Depot
Gardner Bender 1/2 in. 1-Hole Plastic Cable Clamps (12-Pack)-PPC-1550UVB - The Home Depot
HILLMAN 404669 3/16-Inch X 1/2-Inch Black Nylon Cable Clamp at Sutherlands
