This "made for the mushroom industry" drill bit is for use with sawdust spawn inoculations and is a perfect match for our handheld brass sawdust spawn inoculation tools. The machined drill bit stop sets the depth to match the tools' volume resulting in properly filled inoculation sites. A self-feeding screw tip pulls the bit into the log. Our most popular selling drill bit, the 12mm soft steel bit is best used with drill tools turning over 2,500 rpm and has excellent performance in our angle grinder adapter. This bit will drill about 300 logs before it will need sharpening.