Top has a large clear plastic window for best viewing of the incubation and hatching process. Picture window is double plate plastic with air space insulation to help eliminate moisture buildup, which would obstruct viewing. Large viewing area is ideal for classroom work, science projects, advertising and promotional work, and for group observation of the hatching processes. The No. 1583 is a circulated air model. Without a turner in place all Hova-Bators will hold any size egg, from 130 small Quail eggs, up to 50 large duck eggs. This unit is equipped with our dependable and easy to use wafer thermostat. Dimensions: 18'' x 18'' x 9 1/2'', 110 Volt AC,, 25 Watt ( 220 Volt Available for export). All Hova-Bator incubators include a sanitary plastic liner (item No. 1765).. Returned items subject to 20% restocking fee.