Knock box Coffee grounds knocker Is a device for knocking out coffee grounds. In order to process soap making products for other uses, such as scrubbing the skin with coffee grounds, discarding as tree fertilizer It's a box of many shapes. There is a sink, stainless steel knock box. Put in the outer wooden box, ABS plastic, with weight, so it will not slip when knocking the coffee grounds For example, the Tubbi knock box is another device for coffee shops.