Tap bolts are similar to hex bolts except they are fully threaded no matter what their length. They are designed to be used in drilled and tapped holes. They are used in applications where a stud with a nut on each end would be impractical. Used in low strength applications. Stainless Steel material. Grade 18-8 has the same design advantages as a low carbon bolt, however can be used in environments that require greater atmospheric corrosion resistance.