Ideal for drilling porcelain stoneware for shower doors. Tried a cemented carbide drill bit for masonry but that was a waste. I ordered them and they arrived the next day which was perfect. Not sure how long they will last but I would order again even if they only lasted one job at this price point. I drilled six holes and the last one was just as easy as the first. Don't drive at full speed and keep them wet. I had an assistant who would squirt water about every few seconds to keep it cool.