Socket Shoulder Bolt
Socket shoulder bolts have a ground finish plain section under the head which is often used for rotating or sliding applications.The head is lower than that found on a socket capscrew.
They are ordered by quoting the diameter of the threaded portion, the ground portion being the next size up, for example an M8 thread will have a 10mm diameter shoulder.
Length measured from under the head to the end of the shoulder and does not include thread.
DIN 912, BS3643