Kasfam Face mask, Anti PM2.5 activated carbon mask Filter face masks with 3.0 breathing valve for cycling MTB. 5.0 out of 5 stars 1. SyeRum Anti-Smog Sponge Face Mask Washable Unisex Face Reusable Anti-fog Mask with 3.0 Breathing Valve for Outdoor Sports, Gardening, Travel.