These are custom ribbed neck carriage bolts we supply to one of our oldest customers. They measure 1/4-20 X 7/8 and are manufactured domestically in the USA in Grade 5 steel material, with zinc and clear finish. Production lead time is typically approximately 6-7 weeks for this custom part and all certs are available upon request.
Large quantities of these custom made carriage bolts would be best supplied on a 12 month blanket purchase order basis. The Blanket Order concept allows the customer to access the large quantity cost savings without paying upfront for the entire large quantity order. Instead we take on the burden of carrying the bulk inventory and only release the parts as needed, or often on a pre-scheduled basis provided by the customer.