1. 3 layers of protection: non-woven outer layer + filter paper layer + skin friendly non-woven inner layer. Breathable and comfortable, low breathing resistance. 2. The plastic strip of bridge of nose hides the side of bridge of nose. More suitable for all face types. 3. High elastic flat ear straps: will not strain the ears. 4. Inner layer: skin friendly non-woven fabric; soft and comfortable to reduce the possibility of skin allergies. 5. Physical ultrasonic welding, densification of welding points, strong and durable, fine workmanship. Specification: Size: 17.5x9.7cm / 6.9x3.8in Color: Blue Material: non woven Quantity: 50 pcs. Usage: to block dust, smoke, pollen, dustproof, antibacterial, etc.