Brand: Automotive Racing Products (ARP)
These high-strength ARP bolts are great for installing most accessories.  The 180,000 psi tensile strength bolts are made of 8740 chrome moly with a black oxide finish.  Pack of 5 bolts includes matching washers.  
These bolts have a 3/8-16 UNC thread pitch and 4" under-head length, including the 3" long grip (unthreaded portion).  The hex head takes a 7/16" wrench, but has an oversized 0.70" diameter bearing surface*.  Head measures 0.36" high. 
* Standard AN960-616 flat washers have a 0.625" OD.