Features The top end of the chimney (combustion-air terminal with passage through the roof) - the air intake secured with a net. BI-GAS is a selected and hydraulically optimized sollution which also has self-cleaning properties. The system works under vacuum (it is not equipped with gaskets). CHARACTERISTIC: - diameter: 130/200 mm - temperature resistance: 600°C - tested at CERIC - material: stainless steel (austenitic) 1.4404 inside, (316L, L50), 1.4301 external L20. The complete system is covered by a 5-year manufacturer's warranty.