System1 Designs 3" Inch Black Silicone Coupler 3 Layers of Polyester Reinforcement Suitable 45 Degree Turbo Air Intake Intercooler Piping with 2x T-Bolt Clamps System1 Designs line of silicone couplers feature 3 layers of polyester reinforcement and are suitable for applications with boost pressures up to 45psi. They also feature a temperature rating of 428°F for direct to turbocharger installations. Don't be fooled by cheap '4-ply' couplers, sellers generally use it as a marketing term to mean quality which is often not the case. Our '3-ply' meet rigorous standards and have been field tested time and time again.