Mr. Gasket Header Bolts feature a washer-faced, smaller-than-standard hex head that's perfect for getting into tight spaces. Designed to withstand the abuse of red-hot exhaust ports and prevent leaks created by under-tightened header bolts, they're heat-treated Grade 5 steel, have 3/8 coarse threads and a corrosion-resistant black oxide finish, and come in packs of 100. They're also available in sets of 12 (part number 915).