This high quality exhaust or engine studs produced from corrosion resistant 321 stainless steel in 5/16" X 18"-5/16" X 24" standard thread size are a direct replacement for the TCM Continental part number 402-151 stud. FAA/PMA approved for the Continental engines C-75, C-85, C-90, O-200 series engines, and O-300 (early) series engines.