I needed a large wood bit to cut holes in the countertop to attach the sink. I've read several reviews of other similar attachments online, and some mentioned poor cutting or one-time use. This drill is a BEAST. I've used it several times and it cuts through wood leaving a very accurate clean hole. Without them I could not have completed the sink installation. I give 5 stars because it is exactly what I needed. Tip: Use a vacuum cleaner and hold the nozzle close when drilling to suck up the sawdust, this drill bit cuts fast and leaves a lot of mess.