The design consists of the visual features of the portions of the filter shown in solid lines in the drawings, whether those features are features of one of shape, configuration, ornament or pattern or a combination of any of these features. Throughout the Figures, where shown: (i) the dotted lines showing additional structure of the filter are for illustrative purposes only and form no part of the claimed design; (ii) the unshaded surfaces do not form part of the claimed design; and (iii) the dash-dotted lines illustrate unclaimed boundaries of surfaces claimed as part of the design. Portions of the filter not shown in the Figures and not otherwise described in this Specification do not form part of the claimed design.