We had 5,000 pieces of these custom countersunk double end studs manufactured for our customer that specializes in frozen drink equipment production.  304 stainless steel material was used and the thread was cut on both sides.  Overall length was 41.66MM +/- 0.5 and both threaded sides incorporated 5/16-18 2A thread, at 10.16MM and 15.24MM in length accordingly.  At the maximum diameter point the countersunk shoulder reaches 11.18MM +/-0.2.