This polypropylene rack has slanted sides to help prepare agar media slants in 13-16 or 16-20mm tubes. Media-filled tubes are autoclaved with the rack in a vertical position; then the rack is positioned to the preferred angle and media allowed to cool and harden. One side is inclined 5° to create a large surface area that is ideal for aerobic cultures. The other side is inclined 20° for a smaller surface area that is ideal for anaerobic cultures and reduces drying out of media during storage.