Abstract: The tendency of circular draw plates used in disc cartridges containing a magnetic disc memory to warp during fabrication is significantly reduced by a draw plate which includes two warp reducing apertures each spaced at an angle of 90.degree. from the posts along the circumference of said draw plate. An improved post is disclosed. The post includes a coarse knurl which is urged into a post aperture formed in the draw plate.A ring magnet in the bottom cover is also disclosed. The single ring magnet replaces several pot magnets of prior art cartridges and significantly reduces the cost of producing the disc cartridge. A U-shaped magnet cup into which a magnet is positioned concentrates the magnetic lines of force and thereby increases the magnet's magnetic efficiency.