The Hydro Crunch 4 in. x 25 ft. flexible aluminum duct is ideal for HVAC, bathroom, greenhouse, grow room, grow tent fan exhausting and other general purpose exhaust applications. 3 layers of ultra thick aluminum laminate are included in its composition. Temperature range from 0 to 185F. High temperature resistant. Made from high quality aluminum, not only does the duct act as in intake and exhaust piping for active-cooled fixtures and reflectors, but also stores and dissipates heat at a steady rate, which reduces room temperature fluctuations. Benefits of air duct: helically shaped and internally crimped galvanized steel strip. Interlocking steel strips to form an air tight and leak proof system. Strong and flexible. Improves efficiency of the air flow. Dimension: 4 in. Dia x 25 ft. long. Includes free 4 in. duct clamps (set of 2).