We supplied our customer these low profile hex socket drive "hurricane bolts" in three different lengths: 1/4-20 X 45MM, 1/4-20 X 30MM, and 1/4-20 X 70MM.  18-8 stainless steel material was used on all lengths with commercial passivation.  The rolled thread length was set to 20MM and remained the same on all three options, with the balance being unthreaded shoulder.  Full certs were provided with the parts per customer requirements.