On the basis of the first bullet design, a slight change was made. The way the non-woven fabric was clamped by the inner shell was changed to the way the sleeve was rotated and fixed. In this way, the mask shell is a single layer, which greatly reduces the cost of materials and molds. Design Description: This replaceable filter element type protective mask is designed. The filter part is made of non-woven fabric, which is the same material as the medical surgical mask. The contact face and the strap can be recycled without discarding. When not in use, put one key into the matching storage box for 30 minutes of UV UV disinfection. This can relatively save materials and be used sustainably.