welding filter half-mask 3M™ 9925 against welding gases provides light, effective, comfortable and hygienic protection of the respiratory organs against dust, aerosol and metal fumes; provides protection from ozone and welding fumes, plus relief from nuisance odors; the D marking on these filter half-masks means that the special requirements of the dolomite dust contamination test for filter half-masks (FFP) that can be used for more than just one shift have been met