TBC stands for Tensile Bolting Cloth. MG stands for Market Grade. TBC and MG wire cloth are both used in media screening systems. MG uses thicker wires which help in longevity of screens, but there is less open area on a screen and therefore less media can get through. Contact a Progressive Surface customer service representative to see what will work best for you. A US standard test sieve is used for testing and sizing the media. An #80 MG, TBC, and test sieve are not the same and cannot be used interchangeably. See the Sweco screen chart for details.