A built-in fan improves egg hatching conditions by circulating a constant flow of warm air throughout the incubator. It allows you to improve hatching conditions by closely maintaining the ideal temperature of 99.5 degrees. Constructed of durable Styrofoam to retain warmth. Has two 4″ x 8″ viewing windows, solid state thermostat control, thermometer and wire grill to safely support eggs. 17 3/4″ x 17 3/4″ x 8″.