A breather filter cartridge in a data storage device contains a filtration media, such as packed granular carbon, in a chamber. The cartridge incorporates a gas diffusion path that traverses through the breather filter casing, interfacing with the chamber along a tubular sidewall and allowing the thickness of the filter top end to be reduced. This permits additional filter media to be packed into the same breather filter height. Alternatively, the same amount of filtration media can accordingly be packed into a thinner breather filter. The top end may also include an outward extending flange, with the chamber extending completely through the flange. A thin film seals the media above the flange, allowing for even more filter media to be packed into a breather filter of identical height.