Strong and durable: Our cover is made of cotton, soft and breathable, comfortable to wear and adjustable on the bridge of the nose. They can be used all year round. Reusable: This cover is washable and reusable. It offers you comfort and fashion. Adjustable: Earring cover with elastic cord, you can freely adjust the length of the cover strap as needed. A size suitable for most people, suitable for adults, men and women. Function: anti PM2.5, anti-fog and haze, industrial anti-pollution, vehicle exhaust, dust, second-hand smoke, pollen allergy, keep cold etc. Single size: mask: L * W: 21 * 12cm (8.27 * 4.76in) Package: 1 mask (with 4 pcs x PM2.5 filter paper) -Before using, please clean the mask, please note that the Filter cannot be washed – See measurement. A small measurement error is allowed in the normal range. – If you need to order a filter, the filter is 10 units. In a small package.