1.Grinding with water ;( Silicon disc) (Standard configuration), 2. Grinding without water. (Diamond disc) (Optional part), 3. It can work at three different angles; you can adjust it by adjusting screw (7), 4. How to change the disc. Power off, open the front cover (11), and disassemble the disc (1) (if not convenient enough, you can also dissemble the water spray tube (13) you can change the disc easily in this way.), 5. When duty off, clear up the dust in time.