Once you know what looks you want to have your Tiffany work, choose the corresponding foil.

Copper/Copper: To be used with dense opal glass (if you are going to patinate with copper-patina)
Copper/Black: Can be used with transparent and light opal glass (if you are going to patinate with black patina)
Copper/Silver: Can be used with transparent and light opal glass if you are not going to patinate (use with mirror glass)

The different color combinations are available in various widths.