AN8 Bolts -- Undrilled Head
AN8 bolts have a 1/2-20 UNF thread with 0.680 inch thread length.
A or no A? AN bolts were originally designed to be used with a castle nut and cotter pin, so the base part number indicates a drilled shank. The addition of an "A" at the end (for example, AN8-13A) indicates an undrilled head and an undrilled shank. Undrilled bolts should be used with self-locking nuts.
AN bolt nomenclature can be confusing. Please take a look at our page on Identifying AN Bolt Sizes.