Angle Grinder Adapter Convert a standard 4.5" angle grinder into a 10,000 RPM+ drill for mushroom log inoculation. Made of high quality aircraft grade aluminum for a long maintenance free life. Bit held in place by included set screw. Adapter will hold a drill bit with approximately a 1/4" shaft. Designed specifically for log based mushroom cultivation. This adapter is only designed for plug spawn drill bits and will not properly seat a sawdust spawn bit. Pair with our mushroom plug spawn drill bit for professional grade cultivation.