Recoil inserts are the quick and easy way to repair damaged threads or creating stronger original threads in alloys and composite materials in original equipment manufacture. Made from corrosion resistant stainless steel, they create stronger threads in most materials and simplifiy changeover from unified to metric or vice versa. They reduce thread wear and are interchangeable with other brands of inserts or tooling. Size. 1/4 BSF X 26TPI Length. 1 1/2 x Diameter.