IMPORTANT Note: The filter cotton and filter box cannot be washing. Wide Range of Applications Can be used in a variety of occasions (1) Sawing Work (2) Demolition Work (3) Grinding Work (4) Wood working (5) Renovation Work (6)Suitable for production in cement factories, ceramics factories, shipyards, metal smelting, power plants, stone processing, polishing, interior design, sawdust, wood processing, graffiti painting, wall art, powder processing, etc. When to change the filter cotton ? 1-3 weeks of use time.If the filter cotton is dirty or wet or you feel increased breathing resistance, replace the filter cotton immediately. When to replace filter boxes? 200 hours of use time. Establish a replacement schedule is a need. After wearing it correctly, it should not smell any harmful smells. If you smell harmful smells, please leave the work area immediately and replace the filter box.