Glass Technologys 3M Trizact discs use a 5 step process depending on the depth of the scratched glass. The discs are color coated based on aggression. These progressions are from most aggressive to polish starting with GREEN PINK BLUE ORANGE AND WHITE. In order to achieve effective results users must progress down through the aggressions uniformly from whatever aggression or color is initially used. Example: If damage is removed with the blue aggression a user must then progress to orange followed by white in order to achieve a final result. Blue Disc (Medium) used to remove light to moderate scratching from glass surfaces available in 3 and 5 inch. Can be purchased individually or in 25 50 and 100 pack quantities.