Socket Shoulder Screws are screws that have an unthreaded shoulder below the head to act as a fulcrum for a lever pivoted on it. Variants included in this assortment range 10mm thru 50mm in length and come in M10 and M12 diameters. Full assortments of #33779 contain twelve (12) refills comprised of Hillman item numbers #33780 - #33791.