DuraVent's innovative system for a lock-tight connection for Type B Gas Vent called DuraLock. See the alignment indicators meet; feel the ends grasp together; hear the snap as the connection firmly locks into place. DuraVent Type B Gas Vent is designed to meet the rugged demands of the job site. The inner wall is recessed to eliminate damage in handling. Type B Gas Vent has been engineered to heat up rapidly. It remains hot during the operation of the appliance with minimal condensation in the appliance and vent system. Pipe lengths are available in multiple lengths, 6 to 60 inches, with a full complement of adjustable and rigid fittings. Type B gas vents are not suitable for use with wood-burning or coal applications, industrial ovens, exhaust ranges and hoods, grease or pollution ducting, or as free-standing exhaust vents for high-temperature applications.