The raw materials that are used for the production of our finished products are acquired in minimally processed or unprocessed states; these are free from impurities as well. Buy the best quality Polyurethane Tube CLEAR 4 x2.5 Multitech Blue at rock-bottom from us. We are a reckoned name in the town. The outer diameter of our Blue Multitech Polyurethane Tubes (4mm x 2.5mm) is 4mm whereas the inner diameter is 2.5mm.