Stainless steel shelves include 200-watt heater and sensor probe. FreeZone Bulk and Small Tray Dryers include three and can accommodate two additional Heated Shelves with Sensors. The Sensor, included with the Heated Shelf, may be used to monitor sample or shelf temperature. Shelves for Bulk Tray Dryers are 12.7" x 17.0" d (32.2 cm x 43.2 cm) each. Shelves for Small Tray Dryers are 10.6" w x 12.0" d (26.9 cm x 30.5 cm) each.