Abstract: A filing system features a novel compressor in combination with a three rod filing tray. The compressor includes a first compressor part having a first bearing means adapted to releasably engage a centralmost of the rods and mounting an anti-tilt bar removably disposed above and to bridge across the rods; a second compressor part pivotally connected to the first compressor part and having a second bearing means normally biased for engagement with the centralmost rod for releasably retaining the compressor in desired position lengthwise of the rods. The compressor parts may be employed to alternately engage with file material arranged adjacent front and rear ends of the tray.