DuraVent | Roof Top Term Kit Round Type B Gas Vent 3"-6" Inner DiameterCrafted with precision, the DuraLock Type B Gas Vent Kit boasts rugged construction. Its strong, galvanized steel outer pipe features internal spacing beads, creating a uniform insulating air space between pipe walls. This design ensures durability and reliability for years to come. Each end is die formed, guaranteeing uniform sizing and easy, secure connections. In Canada, select lengths are available in galvalume steel outer pipe, meeting diverse