U-Drive screws are round head metallic drive screws having multiple start threads of large helix angle, with a pivot. Featuring case-hardened threads, designed to be harder than the mating part. The Type U-Drive Screw is used when an attachment is not meant to be removed. It is driven into an undersized hole for great adherence, usually in metals or plastics. U-Drive Screws also have a round, unslotted head, again intended for a permanent fixture.