ATV Tek Comfortable and Washable Bandana Style Dust Mask (Camo, One Size) The sewn in interior filter blocks 99.5% of all dust particulates. The Rider Dust Mask also has (2) one-way exhaust valves which reduces lens fogging, releases heat, CO, and water vapor. Made from a breathable, moisture wicking material that keeps you cool and comfortable. When the mask gets dirty, simply remove the tek valves and wash it! Allow the mask to air dry. The universal size accommodates neck sizes up to 20".