I used at least two drill bits to drill drainage holes in the bottom of the couple's ceramic flower pots. I drilled a few 1/4" holes and then a few 1/2" holes in a larger pot. All holes came out nice and clean and cut through surprisingly quickly with water as a lubricant. I just used a variable speed cordless drill. The only thing I don't really know is how long they will last, obviously I have nothing to compare and I haven't used them long enough but for the price they seem like a good deal. It's not something I plan to do every week, maybe more often, just once a year, at which time I might lose her.