These are custom 316 stainless hex bolts made domestically in the USA in 316 stainless steel material.  The thread pitch made this hex head cap screw a custom production deal, at 13/16-10 fully threaded.  The thread was rolled rather than cut and the head width across the flats was set to 1-1/8 inches, with the head height set to 15/32″.  Material certs and a certificate of conformance was available upon request.