Standard: DIN 7981C. Pozi No. 1 1 2 2. Pozi Drive Depth (t) 1.35 1.83 1.93 2.16. Pozi No. 2 2 3 3. Pozi Drive Depth (t) 2.34 2.74 2.97 3.48. Self tapping screws cut their own path into material. They have sharp cutting ridges that allow them to slice into the material without pre-drilling a hole.