The RZ M2 mesh mask is our second generation design. It features a highly breathable, comfortable and durable mesh fabric construction with an adjustable hook and loop closure in the back that makes taking it on and off a breeze. The M2 is excellent in the summer heat, it's also known to stand up to those negative temperatures. Each M2 RZ mask includes two of our standard F1 active carbon filters, but you can upgrade yours to our F2 high-flo filter or an F3 high-flo + active carbon filter, all of which tested to be 99.9% effective blocking particulates down to 0.1 um. For those with an eye for a little extra flair, you can customize your mask with one of our V2 valve color options.