Squirrelly 4" to 3" Inch Black Silicone Reducer Coupler 3 Layers of Polyester Reinforcement Suitable High Level Turbo Pipe with 2x T-Bolt Clamps Squirrelly's 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. Features: Coupler Size: 4 to 3 inches Temperature: 428 Degrees F (220 C). 3-ply Polyester Reinforced. Includes 2 T-bolt clamps Perfect for air intake, intercooler piping and other turbo applications.