Whether it is a professional file or not, it can't be used to polish the nozzle. Files are used to polish hard things like AB or toothpaste to fill the soil. LZ can use sandpaper if he wants to go to the water outlet. Domestic 1000 will do. The net price is about 50 cents, which is very practical. Don't buy Tamiya in Japan, it's too expensive and boring. I hope LZ is satisfied.