This is a Black Emery Stone, a spare part of 10 inch (250 mm) Vertical Type Flour Mill. These stones are made of a hard, abrasive material that effectively breaks down grains. It is a premium-grade grinding stone set designed to deliver efficient, smooth, and uniform grinding performance. It is specifically crafted for 10-inch vertical flour mill models, this pair of stones ensures fine grinding of wheat, rice, pulses, spices, and other grains while retaining natural nutrients. This black emery stone is also easy to install and replace, they guarantee steady performance, reduced maintenance, and high productivity for mill owners.