MUSHROOM DRILL BIT, WHAT MAKES IT SO GREAT? TO INOCULATE A LOG YOU WILL DRILL 30-50 OR MORE HOLES, THIS BIT SCREWS IT'S SELF INTO LOG AND KEEPS GOING TILL IT HITS THE STOP, WHICH THROWS OUT DRILLED WOOD AND LEAVE A NICE ROUND HOLD THAT IS NECESSARY FOR THE INSERTION OF PLUGS /DOWELS. WE NEVER FOUND ANOTHER TYPE THAT WAS AS GOOD AS THE SCREW TIP TYPE SOLD BY OTHER COMPANIES, SO WE COMBINED THE BEST OF THE 2 TYPES USED IN THE MUSHROOM INDUSTRY AND NOW WE HAVE A BIT THAT WE FEEL IS FAR BETTER THAN THE OTHER TYPES! This is a special made drill bit that is made for the drilling of holes for the fast insertion of the mushroom inoculated plugs. These are custom made only for us and not available to any other company and are made with the best of several bits already used in the industry. You will notice the screw tip which drills itself and behind that is the cutting edge that can be sharpened. The shank is a half shank that resist warping due to high heat (A very bad problem with the screw shanks). There is a stop that is built into the bit, so there is no need to purchase one, saving you the extra cost and time. After the stop is the shank that is like all other bits. These work best if used in high speed drills. We use a 10,000 RPM drill and can drill 10 holes in 9 seconds ! OK, you don't have the zippy little 600 dollar drill (and it's not sold in USA anyway)? We drilled 10 holes in 25 seconds with  18 volt cordless drill   It is even a lot faster with the new cordless and certainly a top brand. Some will convert angle grinders with a drill chuck sold in Home Depot if they are going to be doing more than a few logs every year.