An economical venting system used for relining masonry chimney for natural gas or liquid propane category I, draft hood equipped appliances, and appliances tested and listed to use Type B Gas Vent for a wide range of applications, including: natural gas fireplaces, gas-fired furnaces, boilers, water heaters, and wall or space heating applications. Protects the masonry chimney from damaging effects of flue product condensation. Simpson Dura-Vent has changed their name to DuraVent. DuraVent is a recognized technological leader in the venting industry. Consistently the first to market with new innovations in venting systems, DuraVent has captured a leadership position in emerging markets. DuraVent has patents for several products and continues to design safe and technologically advanced venting.