1. Brush the floating soil with a small brush, which is suitable for backpacks with only floating ash.
2. Use a soft towel to wet and dry. It is suitable for backpacks with common stains (such as mud).
3. Soak in a large basin for a few days and rinse it repeatedly. It is suitable for dirty backpacks.
4. Dismantle the backpack system and use the washing machine. It is suitable for lazy people with cleanliness.