Ribbed Neck Carriage Bolt (Drawing in the attachment) round/flat head rib neck carriage bolt M12 1.75 x 40 MM The knurl part needs to be a minimum of 10 mm but could be up to 15mm C1038 steel, grade 8.8 zinc, bake and yellow chromate Test order: 100 pcs Final order: 50000 pcs/year