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 1/2-20 UNF threads and a 4" under-head length, including the 2 3/4" long grip (unthreaded portion).  The hex head takes a small 9/16" wrench, but has a 0.85" diameter bearing surface*.  Head measures 0.45" high. 
* Standard AN960-816 flat washers have a 0.875" OD.