We carry the square dehydrators which have a horizonal air flow. Most round dehydrators use a vertical air flow and are not as versatile, a nightmare to clean and they don't dry as well.
On most round stackable dehydrators the heating element, fan and electrical controls are located at the bottom - beneath the food. This can cause electrical problems as well as being difficult to clean. The more trays that are stacked, the further the food is away from the heat, dramatically increasing the drying time, and requiring frequent tray rotation day and night to prevent spoilage.
The square dehydrators have a rear-mounted heating element to warm, and a rear mounted fan to push the air horizontally over each tray. New air is drawn in the rear, and moist saturated air is pushed out the front. When done remove the trays and wipe the seamless bottom clean of any drippings.