That looks like an ordinary straight piece of automotive emissions hose, which is made out of neoprene. Just measure the inside diameter of an unstretched bit, or take the hose, and visit Repco or a speedshop such as Autobarn or one of those. They sell it by the meter. Make sure you buy neoprene automotive hose though - it is not damaged by oil, at least for a decade or two. And buy the right size, they have it in a multitude of sizes.
