The Techno™ Filter Twin Pack contains two replacement filters for use in your Respro® Techno™ Mask. The filter is suitable for use in heavily polluted environments, i.e. air that is full of diesel particulates and respirable dusts that lodge deep within the lungs and air sacs.It is a combination of the Sports™ filter and the City™ filter giving you both sub-micron particle filtration with gas and vapour filtration. What this means is that the filter is able to trap particles less than one micron in size.This filter can be used with any Respro® mask (with the exception of the Metro™ mask) provided that it is the same size filter as the mask size ie; large filter - large mask.