Socket Shoulder bolts are fasteners that have an unthreaded portion of the shank that functions as a bearing surface or spacer. These are measured by the Shoulder Only, for this size the shoulder diameter is 5/8", the length of the shoulder is 1 1/2" and the thread on the end is 1/2 12 TPI BSW. It is important to note the threaded portion is NOT included in the length. They have an in-hex drive and are fastened using a hexagonal wrench also known as an Allen key. Use Allen key size = 5/16"
Thread = 1/2- 12 TPI British Standard Whitworth
