The screws are wood screws in a black oxide color. The screws are versatile - a Phillips or flathead screwdriver can be used.
These help you fasten oil paintings, stretched canvases, plexiglass, mat, backing, mirrors, etc. into frames that are flush in the back. These are great since they do not break off easily and can be reused on other frames as needed unlike framer's points.
If you have any questions/concerns, feel free to ask. Thank you!