Roll of 656 Feet. BradyMark Marking foil provides a highly legible, permanent legend for PVC insulation and sleeves, polyolefin heat-shrink sleeves, nylon (including THHN-THWN) and many Teflon applications. Foil can be imprinted with low heat. Feed advance is easily regulated to match wire diameter or material to be marked. Foils are formulated for specific applications. Be sure you have selected the right foil for your application.