Spectre air intake couplers and reducers come in variety of shapes and sizes as well as three different materials. The EPDM/TPE is a soft and flexible rubber while the PVC material is rigid and not flexible at all. These two types of material are great for typical cold-air intake setups and stock systems, however they are not recommended for forced induction systems such as superchargers or turbochargers. The Silicone material is manufactured using high quality silicone with a 3-layer polyester reinforcement. Silicone Spectre Air Intake Couplers and Reducers are designed for temperatures up to 385°F. These couplers & reducers are NOT recommended for use with supercharged and turbocharged systems.