Absolutely the worst parts I have ever bought. I use an L-lock bit at first and it cracked a bit on a pine tree, but I blamed the tatty Home Depot wood. Eventually, when I got to the point of using tongue and groove cutters on a good poplar, he was just trying to burn his way through. I wasn't expecting the quality of a Freud bit, but I have sharper screwdrivers than this one. Unfortunately I've had them way too long before actually using them and I can't get the damn things back. I hope I can save you money too.