1) Multi-purpose drill bit for Hardened Steel 
   Cobalt and tungsten carbide tip,Chrome and vanadium steel shank
   to drill on hardened steel, stainless steel,
   as well as porcelain tile, ceramic, granite marble brick masonry concrete PVC
   metric size: 3-12mm;   Inch size: 5/32"-1/2"
2)Picture of multi-purpose drill bit black fluted

1/8" 2-3/4" Straight

5/32" 3-1/4" Straight

3/16" 3-1/2" Straight

7/32" 3-3/4" Straight

1/4" 4-1/4" Straight

9/32" 4-3/8" Straight

5/16" 4-1/2" Straight

11/32" 5" Straight

3/8" 5-15/16" Straight

13/32" 6-1/4" Straight

7/16" 6-1/4" Straight

15/32" 6-1/4" 3/8"

1/2" 6-1/4" 3/8"

5) Drilling Instruction

Please follow the speed and technique instructions below

Hardened Steel and Iron            2000—4000 RPM (Lubricant)

Masonry/Concrete                 2000—4000 RPM (Percussion)

Stainless Steel                    1500—2500 RPM (Coolant)

Glass/Tile/Granite                  300—600 RPM

Plastic and Laminates               300—600 RPM

Solid Surface Materials              300—600 RPM

Wood and Composite                500—1000 RPM

Drill on different types of materials