It is a professional coffee metal burr hand grinder. 420 stainless steel coffee grinder mechanism inside ensure the accurate grinding size from coarse to fine. There are 5 different options. You can choose the different sizes depends on your different coffee demands. If you want to make an espresso, you can choose the finest size; and if you want to make a cold brew on Summer, you can choose the coarsest size. The totally material of the grinder body is Aluminum alloy. It is durable and can satisfy your long time use.