A construction of filter sock which has a panel (1) with two leaves (2,3) of unequal width such that when folded along a foldline (4) the leaves form a double leaf panel with a projecting side (9). The side (9) is folded back along a second fold line (11) over the free side (6) of leaf (2). The sides (6,9) and leaf (2) are secured together by an overlock stitching (13) to form a tube (12). The invention provides a method of making the filter sock.
