UNC Threaded Spacers\/Inserts, also known as coupling nuts or stud connectors are used to join or space two lengths of threaded bar. These are manufactured in house from EN1A Steel bar using state of the art CNC Machines. Therefore, unless the item is deemed faulty, this item is non-returnable and non-fundable. 5/16" UNC x 22mm O/D Threaded Spacers EN1A Mild Steel 20mm