Selkirk, formerly known as Metalbest or Metalbestos,, is rated at 2100 degree and designed for all-fuel applications. Features include a stainless steel outer casing, 1"+ solid pack insulation, and is UL-103 HT listed. Available in sizes: 6" and 8". Selkirk is for use with heating appliances burning wood, #2 oil, and natural and LP gas. Selkirk has 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.