Polyurethane is short for PU. LZZG choose PU screen as its new type sand washer sieve, because its long service life and not easily blocked in screening. When processing coal mud or dirt mixed water, steel mesh is easily blocked and adjusting its mesh size will highly reduce its capacity. LZZG new type sand washer is already successfully perform in silica, limestone, quartz, river sand, coal....washing, screening & dewatering process. see product details: http://www.hiwtc.com/products/ts-dewater-screen-and-xsd-washer-working-site-8985-1102587.htm