Review on Utoolmart Multi Material Blackening Concrete Plastic by Kenny Marozas

Bit works great on clay/ceramic pots. I drilled a drainage hole in a small aquarium glass pot and the glass was a lot harder to drill and cracked a bit too, but that's ok. I highly recommend if you need to drill holes in softer materials, but if you need to drill through glass or a mirror spend the money because you get what you pay for. 12mm diameter drill bits are ideal for drainage holes!