Abstract: A filter bag for dry copiers, i.e. copiers which employ particulate toner material. The bag comprises a filter element and a protective cover of porous non-woven material which imparts negligible resistance to air flow.

Abstract: A self-supporting, self-gasketing, multi-stage, variable density glass fiber sleeve filter is disclosed and includes a reusable internal wire frame with a composite, low velocity fluid entry filter member on one side of the frame and a fluid egress member on the other side of the frame. The fluid entry filter member is made of two or more layers of medium to long filament puffed glass fiber that differ in thickness and density. The entry and egress members are stitched along longitudinal edge portions so as to form an open ended sleeve that can be slid on and off of the reusable frame. The sleeve is dimensioned such that when it is slid onto the frame both the entry and egress members are tensioned across the frame such that the entry member is outwardly curved with respect to the egress member.