... proof finish, Superior tensile strength, Dimensionally accurate, Highly durable, Light in weight, Competitive prices, Superior finish, High durability, ... )TOLERANCES: Wall Thickness:Light Tubes+not limited -8%Medium & Heavy Tubes+not limited -10%Weight:Single tube (Light)+10% -8%Single ... to 6" - 11 TPI8)MARKING:Tubes are distinguished by colour at two ends. .Light tube-Brown, Medium tube-Blue, Heavy ...