SMC is a combination of chopped glass strands and 
  filled Polyester Resin in the form of a sheet. 
  Primarily used in compression molding. The SMC 
  manufacturing process allows glass percentages from 
  15% to 65% to be incorporated into the matrix. 
  The glass length can be increased up to 2" vs. a 
  BMC that may range between 1/8" and 1/2". SMC also 
  offers the possibility of continuous strand or matte. 
  Have smooth surface, beautiful color, high-strength, 
  excellent insulating performance, anti-corrosion, high 
  production efficiency. They are widely used in many 
  fields such as electronics, electrical, auto parts, 
  water tank, instrument, civil installation and decoration. 
  http://www.fiberglass-cn.com