CONVENIENT FOR CANDLING EGGS - Weighs only 5 ounces - easy to move over eggs for long periods - eggs need not be handled. It has a 5-foot electric cord. Candle eggs to check progress of development. Hold the light up to the large end of the egg in a dark room. After 10 days check for infertility (entire egg will glow). Remove infertile eggs from the incubator to provide more room for hatching chicks. Two or three days before the projected hatch date approximately 1/3 of the egg should show an air pocket. Returns may be subject to a 20% restocking fee.