Answer: 1. This kit adopts the principle of repair of “grinding followed by polishing”. Grinding has two steps: coarse grinding and fine grinding. Coarse grinding, which fine grinding and polishing follows, is to get scratches off. Since the sheet for coarse grinding has big grinding particles, the grinding efficiency is very high. Taking an example, a 5 cm long scratch left by a stones or sand can be got off basically in 1 minute. Facing more serious scratches or burning by welding slag, you need only extend coarse grinding before fine grinding and polishing. Thus, the kit can repair all scratches no matter how serious they are.
2. The kit can repair all scratches no matter how deep they are. Not to mention the length. If scratches are too long, we advise you repair them in segments.