The Nesco FD-79 Food and Jerky Dehydrator provides the drying power that generates maximum speed and quality for dehydrating your favorite foods. The adjustable digital temperature control 90F -160F gives you the flexibility to achieve the best results when drying different foods that need varying temperature settings. The digital timer is programmable for up to 24 hours of drying time and includes an auto off function. This dehydrator comes with four 13-1/2 diameter trays and expands up to 12 trays so you can dry large quantities at once, with no tray rotation needed. Additional Add-A-Trays sold separately. The quiet, powerful Converga-Flow fan forces heated air down the exterior pressurized chamber, then horizontally across each individual tray.