This item seemed to be the answer to my CNC needs; Being able to change blades instead of changing the whole bit. Worked fine for a couple of weeks until the drill itself broke just above the blade. Now I have a couple of blades that are a bit broken. I hope it was a fluke and I'll buy another one (even if the price goes up $15 a month!). If the seller takes care of their customers, they refund me $ for the first one.