An assortment of heat-treated metric hex keys from The Hillman Group. Also known as Allen keys, hex keys are L-shaped tools used to drive bolts and screws that have a hexagonal socket in the head. The contact surface of the screw or bolt is protected from external damage. Variants included in this assortment range from 1.5mm to 10mm in diameter. Full assortments of #1541 contain nine (9) refills comprised of Hillman item numbers #1542 - #1550.