Product presentation:Performance indexaccord with the standards of the solar grade and above for Etching-free (GB/T25074-2017). The surface has slight pits with depth≤ 5mm(the surface is slightly rough without visible holes),Dense cross section,No discoloration, discoloration, no visible pollutants and oxidization or After cleaning the polycrystalline silicon to achieve no pollution, sundries, oxidation ,To be satisfied with the needs of customers for directly cast furnace using.