It has an Internal Rubber lining combined with closely woven polyster fibre. It also has a smooth inner lining surface with very low friction loss.It is ribbed for Hose protection and easy handling.It requires zero maintenance. Tube: Synthetic Rubber –Black Reinforcement: One Braid of High tenacity yarn Cover: Synthetic Rubber-Blue & Red Working Temperature: From -30 °C to +70 °C continuous operation