Glass Technologys 320 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 320 disc is the least aggressive material for light scratches. This material is the last step in the heavy duty resurfacing process prior to polishing. 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.