LS engine guys, this header bolt kit is exactly what you need for your exhaust installation! The pack includes 12 M8x25mm flanged hex socket head bolts plus 12 washers - everything you need to get your headers mounted up properly. These fit a ton of GM LS engines including LS1, LS2, LS3, LS6, LS7, and the Vortec truck engines like the 4.8, 5.3, 6.0, and 6.2 liter versions. They work with most aftermarket headers and factory exhaust manifolds, making them super versatile. The grade 10.9 rating means they're strong enough to handle the heat and vibration of exhaust systems without backing out or breaking. The flanged hex design gives you good wrench clearance in those tight spaces around headers, and the socket head lets you use allen keys for installation. I used these on my LS3 swap and they went in smoothly with no issues - the threads were clean and the length was perfect for my headers. They're black finished which looks clean and helps with corrosion resistance. Just remember - these won't fit pre-97 small block Chevy engines, they're specifically for the LS platform. Whether you're doing a header install on your Camaro, Corvette, Silverado, or any other LS-powered vehicle, this kit has you covered with quality hardware that gets the job done right. The price is reasonable for a complete set, and having all the bolts and washers together makes the install so much smoother. Definitely recommend for any LS header project!