Weiler 7/8 Single Spiral Flue Brush .012 Steel Fill- Filled with .012 round wire and fitted with 1/4 x 2 NPT pipe nipple. For internal cleaning of pipes and flues. Flue Brushes are designed and engineered from black oil-tempered wire. Flue brushes are available in single spiral and double spiral construction. Other fill materials and sizes available by special order. Flue Brushes provides increased conformability and long life when: Pipe cleaning Flue cleaning and Boiler tube cleaning. Engineered and manufactured to maximize performance and minimize operating costs. The use of superior construction the highest quality materials and the most stringent manufacturing processes deliver the lowest cost-of-use and most consistent performance.