The Counter-Snap hardwood floor screws ,for use between the joist,are designed to pull then snap at the weak spot on the screw. The fixture when used with the screw snaps the screw head off 1/4 inch below the surface. The small hole that is left can be filled with a small amount of wood filler to conceal it. Simple.
The video below explains the best how the tool works.
The kit includes 50 scored screws the snap off fixture and a driver bit.