Commonly used on the Cessna 150 & 172. Stud lengths are stamped on the head. The 82 series fasteners are phillips, while the 85 series are slotted. The third number group indicated stud length. Made from 1008 steel. Finish Dacronized steel with zinc flaked chromate coating. 82 series are .196 diameter. Example 82-19-120-16 The 85 series are .250 diameter.