Make your life easier with our Flat Head and Round Head Machine Screws - they have the Square Drive advantage! And they are zinc plated for light corrosion resistance. Flat head machine screws have a standard 82 degree countersink design similar to that used on our Square Drive Production wood screws. Pan Head machine screws have a special head design that combines a square recess with a slot, as shown. It’s made like that because of its extensive use on Canadian manufactured electrical distribution hardware (like circuit breaker boxes). Both screws are threaded the entire length of the shank. USA or Canada.