With the Brinsea OvaView Standard Bird Egg Candler， you can safely candle eggs without harming the embryos. This candler uses high efficiency LED illumination which won’t cause heat damage. A flexible black ring creates a seal against the egg shell for optimal viewing. You can use this candler as a hand-held device， or you can place it on a work surface. It’s powered by the included set of four AA batteries， but you can also use rechargeable batteries. This candler is ideal for monitoring the embryo development of pale， plain shells， including those laid by most hens， ducks and geese.