HD Version with inner pipe, more durable but still flexible, cmpletely made of Stainless Steel, gas tight and extremely stable BOOST Products Flexible Bellow HD 30mm HD Version with inner pipe, more durable but still flexible Completely made of Stainless Steel, gas tight and extremely stable This compensator has an inner pipe what keeps the gas flow straight and avoids the direct heat to the outer flex waves. But the inner pipe makes the inner diameter smaller, where we recommend to use always one size bigger than at the standard compensators. Best purpose is the construction of Wastegate pipes, downpipes, exhaust systems or manifold construction. The BOOST Products Flex Pipe Compensators are extremely resilient but still flexible. Completely made of Stainless Steel. IMPORTANT: A compensator compensates like the name says expansions caused by temperature. For example Wastegate pipes before and after the turbocharger. It serves to compensate the expansions on these spots to prevent cracking of these pipes. It is not in the position to absorb heavy load and is thereby not suitable as a Flex Pipe substitute. Here we recommend a reinforced Flex Pipe from our product portfolio. Material: stainless steel 1.4301 / SS304/ V2A Outer diameter exhaust pipe: 31mm Inner diameter exhaust pipe: 29mm Inner diameter HD pipe (intenal pipe): 28mm Length: 72mm Note: At all messurements are slightly differences possible because production procedures. 5 Years BOOST Products Warranty For this item you receive 5 years warranty in the Area of the Federal Republic of Germany, additionally to the legal guarantee. The processing is handled directly by BOOST Products GmbH regarding the BOOST Products Warranty Terms. You find these at www.boost-products.eu/en/cont/warranty-conditions/ .