RZ Mask Filters - 3 PackDue to COVID 19, all RZ Mask Filters sales are final. Please make sure your Filter size matches your Mask size. The RZ F1 is the standard filter of RZ Mask and consists of two filter layers the outer particulate filter and the internal active carbon element. The outer layer of the F1 filter is capable of trapping particulates down to . 1 micron in size. The inner layer, known as the Active Carbon element, is effective towards fumes and odors.