Glass Technologys 120 heavy duty glass scratch removal discs is the next generation of glass restoration materials. Use this disc exclusively with our Heavy Duty Scratch Hog. The 120 disc is the coarse aggression of materials for heavy scratches. If starting with this material progress to the 320 material and then to polish.FOR ANYONE CHOOSING TO USE THIS EQUIPMENT: PLEASE REFERENCE OSHA REGULATIONS FOR YOUR OWN PERSONAL HEALTH AND SAFETY (1910.1000/132). ADDITIONAL PRECAUTIONS SHOULD BE EVALUATED FOR THE SAFETY OF PEOPLE THAT ARE IN DIRECT CONTACT WITH THE REPAIR AREA. ALWAYS WEAR PROPER RESPIRATION EQUIPMENT.