These premium hollow-spindle drill bits are designed specifically for your CHALLENGE EH/MS/HandyDrill drills. These bits are a consumable item, and should be either re-sharpened or replaced periodically.
These bits are avaiable in standard, or an optional Teflon coating. This coating provides lubricity to the inside and outside of your paper drills. The Teflon reduces friction to increase the wear life of the cutting edge. This is a very good coating for keeping slugs from building up and breaking the paper drills since slugs flow smoothly without binding.
Don't forget to also turn/replace your drill blocks!