If you've always wanted the stylish look of a angled cut tip but couldn't due to the fact you really needed the safety of an external flapper then we have the answer you've been looking for. These high polished 316L stainless steel external flaps are designed to slides over an existing 4" straight cut tip and provide the security of a secondary or even primary exhaust flapper. 1" of exposed exhaust pipe is required for mounting. Sold in pairs.