50 Piece 2.5 P.M Multi-layer Protection Mask Filters : These Mask Filters are crafted with five layers of support that contains activated carbon and non-woven fabric. It helps block pollen, dust, pollution, keep you safe and healthy. P.M 2.5, ideal to protect your mouth and face from Dust, Haze, Smoke, Pollution, Ash, Pollen, Gardening, Crafts.Reasonable size: filters size measures approx. 4 5/8 inch by 3 inch Adult, compatible with most filter masks.