Abstract: Bracelet-shaped filter device molded of plastic has a frame surrounding a slotted filter portion and integral retaining portions which permit it to be held tightly in contact with the surface of a pipe. The filter portion contains a plurality of evenly spaced slots which are positioned so as to be spaced at a predetermined distance from an aperture in the pipe through which fluid may pass. The filter slots are V-shaped and of increasing width in a direction toward the center of the pipe. In a preferred embodiment, the retaining portions are integral straps which can be tightened and held by an integral fastener. In a modified structure which is suitable for small tubes, the device may include curved portions which are adapted to be spread apart and snapped over the sides of the tube. The devices are especially useful to prevent entry of the solid particles in a fluidized bed into the fluid supply conduit.