Abstract: A filter device including a separable housing and cannister-like means, with the improved filter element retained in the latter. The filter element being an elongated tapered strip having a predetermined transverse dimension at its midsection generally equivalent to the diametral measurement of the interior of said cannister and the initial configuration of the tapered sides being equated to the various chordal dimensions of the interior of the cannister-like means integrated with the folds of the filter element, thereby providing a filter element of controllable increased filtration area.