WOOD SCREW is also called WOOD BOLT, which is similar with machine screw, but the thread on screw is special for wood screw, can be screwed directly into wooden component (or part), fasten the metal (or metalloid) part which has a hole together with the wooden component tightly. This connection is also a detachable connection. Wood screw strength is small and can only be used in a soft place, the thread for wood screw is larger than machine screw of same diameter. and the front end gradually pointed. The diameter of wildly used wood screw is 2-4.5 mm or so, meantime no matching screw nut. Generally its operated by a word or cruciform screwdriver.