Hex Drive Size: 9/16"; Width From Flat to Flat: 9/16"; Overall Height: 15/32"
Made of 304 Stainless Steel (no coating outside) which is superior to regular steel and any zinc plated fasteners, provides good strength and corrosion resistance in bad environments.
Will NOT COME LOOSE: With a nylon insert inside, the lock nuts greatly reduce loosening under vibrations and torque.