These are High Speed Steel drills and can be used on many kinds of materials..  They will allow you to make pilot holes in very fine detail patterns.  You can match a drill bit to the size of your blade.  Refer to my blade chart to find what drill sizes are recommended for each blade.    "Blade Chart"

# 75 Twist Drill  =  .021" Diameter         Choose Quantity :         

# 70 Twist Drill  =  .028" Diameter         Choose Quantity :         

# 68 Twist Drill  =  .031" Diameter         Choose Quantity :         

# 66 Twist Drill  =  .033" Diameter         Choose Quantity :         

# 61 Twist Drill  =  .039" Diameter        Choose Quantity :         

# 56 Twist Drill  =  .046" Diameter         Choose Quantity :         

# 54 Twist Drill  =  .055" Diameter        Choose Quantity :         

1/16 Twist Drill  =  .062" Diameter        Choose Quantity :         

# 50 Twist Drill  =  .070" Diameter         Choose Quantity :