I have my own custom glass shower door installation business and use a ton of tile drill bits. I like them, the price is definitely right. 5mm is the correct size for a 3/16 inch hole. You'll need to have a small cup of water ready and stop about every 6-7 seconds to quench the bit in the water, otherwise the weld could get too hot and you'll lose your tip in the tile. It cuts through ceramic like butter, but natural stone will require you to drill with a slight circular wiggle motion or use…