Tube - Specification: Tube material: Polyurethane, Tube Colour, Black, yellow, Red, Blue, Sliver & transparent, Tube Outer Diameter (in mm) - 4, 6, 8, 10, 12, 14 & 16, Tube Inner Diameter (in mm) - 2, 2.5, 4, 5, 5.5, 7, 8, 10 & 11. Features: Provide differentiation of air line in pneumatic circuits