Slotted round head machine screws are ASME standards specific. These fasteners are installed with flat or slotted screwdriver. Round Head Machine Screws feature a domed top, similar to a button head but shaped more like half of a sphere. Slotted head machine screws are often used with nuts as well as driven into tapped holes. In practice, they tend to be mostly available in smaller sizes and the smaller sizes are referred to as screws, or less ambiguously as machine screws, although some kinds of machine screw can be referred to as stove bolts.
Silicon bronze Slotted Flat Head Machine Screws are made of copper, silicon, and various other alloys such as zinc, tin, iron and manganese. Silicon Bronze Machine Screws are used in marine environments, corrosive environments, and high heat environments. Often used in plumbing and electrical applications, silicon bronze fasteners are also found on tattoo machines and in power plants. Silicon bronze is similar in color to copper and is sometimes used in finish applications for the color.
Please note that color and sheen may vary for brass and silicon bronze fasteners.