Self Tapping Screws are designed to advance when turned, creating their own threads in the material. They are often used in sheet metal and plastic. 

Stainless steels are used for their corrosion resistance, high-temperature strength, scaling resistance, and low-temperature toughness.  These properties account for their extremely wide use in practically every industry. Austenitic Stainless Steels are alloys of iron and carbon that contain between 16% and 30% Chromium, a maximum of 0.15% carbon, along with Nickel (or Manganese), and other alloying elements.  The chromium, which helps develop a passive surface oxide film, provides corrosion resistance in stainless steels.   Austenitic Stainless Steels are designated by a 3 digit SAE Stainless Steel Grade beginning with the number 3 (e.g. 304, 316).  Another common naming convention for Austenitic Stainless Steels are 18/8, 18/10, 18/0, etc. where the 18 refers to the % of Chromium and 8 to the % of Nickel contained in the material.    

Flat head fasteners are designed to fit flush to the surface when used with countersunk holes. Length is measured from the top of the head. Common applications for slotted screws include woodworking, although the drive style is not designed to be used with power drivers.