All grades and classes of all types of Carriage Bolts (aka Shaker Screws) are manufactured at TRAMEC Hill Fastener. Originally used for assembling carriages, they are used for more versatile purposes these days. Whatever the use, they can make them to standard (ASME B18.5) with short square, long square and fin and rib-necks. Or, you can challenge them with a print of your own.