Zinc, round-head, combo-drive machine screws have a machine-cut thread throughout the length of their shank. Fasten with either a Phillips or slot screwdriver to reduce risk of over-tightening and protect the screw and fastened material. If nuts are needed, use with nuts of the same finish and threading for proper fit. Use for any indoor or outdoor projects. #8-32 coarse thread x 2-1/2" length.