3 rolls 3/16" BLACK BACK COPPER FOIL (1.25 Mil) 3 Roll - 3/16" BLACK BACK Stained Glass Copper Foil 1.25 mil (31 microns) Thick 3/16 IN X 36 YDS (4.7 mm X 33 M) Black coloring on adhesive (back) side of foil allows use on clear glass, etc. where a black patina is used on the soldered surface and a black finish is desired.