Sold on Amazon Red Line is manufactured on the basis of productivity, durability, and performance. Red Line is extremely tough, long lasting, high-performing, special quality aluminum oxide abrasive which is applied on superior paper backing ensuring that it lives up to its reputation as being Indasa's premium quality. If you are looking for increased productivity to save you time and money look no further than Red Line. , This premium high performance disc is excellent for HARDWOOD or METAL sanding. It is most effective for sanding oak and for auto body applications. Extra hard grain and latex backing make it one of the most productive discs available.