Home / Products / FA Pneumatics / Tubes and Accessories / Tubes / Polyurethane Tubes Coloured Polyurethane Tubes Coloured Ask Quote Download Brochure Description Specifications Usage Instructions How to Order WH Series – Sizes: Ø4, 6, 8, 10, 12mm OD (Silver, Transparent, Red, Black, Yellow) Provide differentiation of air line in pneumatic circuits