1)>30 years manufactured 2)size:40mm 3)Bulk density:0.3g/cm3,0.5g/cm3 4) The Covering Ball is designed based on the Hollow Ball. Compared with the Hollow Ball, the Covering Ball has a rim around its surface. It is of big void ratio, thermal proof, resistant to chemical corrosion. The height of pressure drop and transfering unit is low. It has high flooding packing factor, full liquid-gas contact, ...