DuraPlus is a triple-wall, 2100°, all-fuel chimney system and is tested to UL 103 HT standards. DuraPlus features two layers of insulation and is available in sizes 6" to 8". DuraPlus is for use with wood stoves, fireplaces, furnaces, boilers, ranges, water heaters or other appliances fueled by wood, coil, oil or gas. DuraPlus is the preferred solution for homeowners installing their own system due to its increased margin of safety.