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: Size: 3" to 2.5" Material: 3-ply Polyester Reinforced Temp: 428 Degrees F (220 C) Includes 2 T-bolt clamps