The 2000 SR Series Ducting is specifically engineered to handle unconditioned air. It can withstand high heat, high humidity and excessive CFM's without any duct failure or fatigue. 2000 SR features a triple laminate with industrial grade foil casing for durability, and an ultra-smooth double sealed core for frictionless and silent air flow. The Carbon Black inner core does not reflect light. Rip-stop prevents tearing, galvanized spring steel maintains duct shape and prevents rust. Made in Canada and engineered for what you need! Sold in cases of 2 only.