Check the listing for details. Senbao Activated Carbon Paper Filters Breathing Protect Replace 20 Pcs 5 Layers. Condition: New. Listed at 21.77 USD. Senbao Activated Carbon Paper Filters Breathing Protect Replace 20 Pcs 5 Layers. Condition is New. Shipped with USPS First Class. Package Include:20 PCS activated carbon replaceable anti haze filter papers. Reasonable Size : 12 x 8 CM/ 4.7 x 3.1 inches; applicable to most face cover on the market. Material:The material is composed of non-woven fabric, activated carbon and advanced filter cotton. Function:Five layers-activated carbon filter can prevent smog, industrial exhaust gas, cigarette smoke, vehicle exhaust gas and other injuries to the human body. Note: 1. The filter element cannot be cleaned, it is recommended to replace it every 1-2 days. 2. When stains of thin film or sticky deposits appear, please replace the filter paper.