THHR Step-Up Black Rubber Exhaust Bellows - 4" x 5" ID

Hump Hose Bellows provide flexible connectors for marine wet exhaust systems. They offer much greater tolerance to heat, misalignment, engine movement and vibration than rigid connectors, with significant savings in cost, parts, labor and space.

These THHR Series step-up, molded single hump exhaust bellows are 100% EPDM* rubber, and are available in 5 step-up sizes from 3"/3-1/2" to 8"/10" ID.
They provide a convenient to connect exhaust system components with differing hose sizes. This most often happens when a component (such as a muffler) is upgraded or replaced.
While these adapters can be used to reduce, as well as step-up, the internal size of the system, it should be noted that engine manufacturers generally don't recommend reducing exhaust hose diameter, as this can increase exhaust back-pressure, which can reduce engine horsepower output.

• Black bellows: made from molded, high temperature, black EPDM rubber. Rated -40°F to +250°F (121°C) continuous maximum, with a 5-year warranty
• Inlet/outlet cuffs are long enough to fit 2 hose clamps
• Also available with (4) included stainless steel T-Bolt hose clamps. See Related Products


High Temperature Hump/Bellows Exhaust Hoses Color Comparison
• Black bellows: made from molded, high temperature, black EPDM rubber. Rated -40°F to +250°F maximum, continuous with a 5-year warranty
• Blue exhaust hoses: made from a very high temperature, blue silicone rubber with or without multi-ply fiber reinforcing (red interior). Rated -65°F to +350°F maximum continuous, with a 10-year warranty
• Red bellows: made from an extra high temperature, red silicone rubber. Rated -65°F to +500°F maximum, continuous with a 10-year warranty

* EPDM is Ethylene Propylene Diene Monomer, commonly referred to as EPDM or EPDM rubber. It can withstand relative high temperatures and exhibits excellent resistance to environmental factors such as ozone, UV, acids, bases, and general weathering.
By comparison, Silicone rubber's outstanding characteristic is its resistance to even higher temperatures, as well as having a longer service life than EPDM. Silicone hose is compatible with water or anti-freeze such as coolant.
Neither of these synthetic rubbers is compatible with fuel or oil, so be careful to protect from exposure.