Now you can use high quality ARP fasteners to install most things on a car, boat or trailer. They cannot beat the gorgeous appearance of the specially polished stainless steel studs and their ability to resist rust. They are truly maintenance free. Nominally rated with 170,000 psi tensile strength. This hardware provides significant additional security over Grade 8 hardware, and the screws are virtually five packed on a card. These bolts feature a traditional hex head, have a diameter of 5/16", a standard thread pitch of 18, a underhead length of .750, and the wrench is 3/8.