High Performance Blue Silicone 2.5" Coupler 45 Degree Angled Elbow Hose 4-Ply. Silicone Hose (Angled Elbow Coupler). Silicone + Polyester. 4-Ply Silicone + 3-Ply Polyester Reinforced. Silicone is resistant to electrochemical degradation, however, are not suitable for use with oil or fuel.