206018/6T-18 6"x 18" INSULATED PIPE | The SELKIRK Chimney System (SCS) is ideal for venting residential heating appliances burning wood, 2-oil and natural and LP gas. They have been specifically designed for today's modern, high-efficiency "airtight" wood stoves. They are designed for gravity (natural draft), non-positive internal pressure venting only. The SCS is usable on any appliance having a power burner (such as an oil furnace) if that appliance operates with neutral or negative draft at its outlet.