I am returning mine because it burned out after only drilling 5 holes in the rock. Revain will supply a replacement and I hope I can report that this is a defective item only as I have never had a problem with many of my other Makita tools. Revain were quick to send a replacement and I am pleased to report that after drilling some significant holes in granite rock the bit appears to be working well. Changed from 1 to 4 stars based on reviews after swapping.