Marking foil is available in black, white and red to match a wide range of marking needs. Foil provides a highly legible, permanent legend for PVC insulation and sleeves, polyolefin heat-shrink sleeves, nylon (including THHN-THWN) and many TeflonĀ® applications. Foil can be imprinted with low heat. Feed advance is easily regulated to match wire diameter or material to be marked.