The stainless steel machine screw has a plain finish and a fillister head with a slotted drive. Stainless steel resists corrosion and may be magnetic. The slotted drive has a linear slot for use with a flat-blade driver. The fillister head has a slightly rounded top and tall cylindrical sides, enabling a deep drive slot for high driving force. This type of screw head is commonly used in counterbored holes.Machine screws are threaded fasteners that are typically used with nuts or drilled and tapped (threaded) holes. Machine screws are available with a variety of head shapes, which determine how the screw interacts with the mating surface, and drive styles, which determine the type of driver required to install and remove the screw.