This mask utilizes end user supplied 38mm / 1.5'' filter material. 1 n95 mask can be cut up to make 5 filters, or any material can be used. Also utilizes a 1 way filter so that exhaled breath does not exit through filter, greatly increasing filter life. Also has strap guides which use 10mm / 3/8'' strap. Here is a link to the valves, https://www.amazon.com/gp/product/B084BVQLBP/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1