Seller: stlhardware (4,186) 99.9% , Location: Saint Louis, Missouri, Ships to: US & many other countries, Item: 391620275181 Qty. 20 - vintage square head machine bolts 5/16-18 x 1 1/2" with square nuts - steel plain finish - thread length is 1 1/4" - surface rust on the bolts and the threads and the nuts - the machine bolts with square nuts will come packaged in a zip lock bag - the box and label was shown for information only and will not be included . I do not know the grade as these are unmarked. New old stock from an oldtime hardware store. Triplex Screw Company, Cleveland, Ohio- Made in the USA Condition: New old stock - surface rust on the bolts and the threads and surface rust on nuts - machine bolts with nuts and will come in a zip lock baggie - these are not marked so I do not know the grade- the box and label was shown for information only and will not be included., Material: Steel, Model: Square Head Machine Bolts with Square Nuts, Finish: Plain Steel, Diameter: 5/16", Length: 1 1/2", Head: Square, Drive: Wrench, Brand: Triplex Screw Company, Quantity: 20, Country/Region of Manufacture: United States, Thread Length: 1 1/4"