Squirrelly 4" to 3 inch Silicone Coupler Straight Reducer Intercooler Hose Intake Piping 3-Ply (Black) Squirrelly's line of silicone couplers feature 3 layers of polyester reinforcement and are suitable for applications with boost pressures up to 45psi. Size: 4" to 3" Leg Length: 3.5" Material: 3-ply Polyester Reinforced Temp: 428 Degrees F (220 C)