Important not: when you buy extra filters pls make sure you are buying right type of filters as there are two different types of filters one air vent filters that not fit one vent/valve Masks only, two air vents filters only fit in two air vents Mask.IMPORTANT NOTE: Before wearing the mask please make sure both air vents are securely LOCKED as we are not responsible if not proper secure or locked and one part fell down as vents work like lock/unlock system to change the filter.FEATURES: Unisex Universal Size - Face shape design, nose portion of an steel sheet secured to prevent slipping and Velcro adjustable size, suitable for most people to protect the face Material - The dust mask is made of mesh/Stretchable fabric and filter activated carbon non woven fabric, comfortable to wear for protecting the face. With good windproof and dustproof effect Unique Ventilation Design - Mouth have ventilation holes, double air valve help you breath easier and freely when riding the bike. The filter can be replaced by yourself expediently Excellent Filtration - Military design mask provides excellent filtration. Built by comfortable and breathable 5 layers filter cotton, it can isolate 95-percent of dust, chemicals, exhaust, smog, fumes, PM 2.5 and particulates Multiple Usage - Suitable for pollen season and outdoor activities such as running, jogging, biking, cycling, riding, hiking, skiing, snowboarding.SPECIFICATIONS: Approximate size: 16 x 16 x 5cm Material: activated carbon non woven fabric