These are custom extra long hex bolts we have supplied our customer for many years, with shipments of approx 20,000 pcs at a time every 2-3 years.  307A steel material is used with zinc clear finish and all parts are manufactured overseas.  1.5″ to 1.688″ of thread is rolled on each part and the hex head height is set to .226-.268 inches.  R0.01-0.03 underneath the head is critical for our customer’s application, allowing the head to lay as flat as possible against the mating part.