Magicfly Bright Cool LED Light Egg Candler Tester, Power by Power Supply Only,Incubator Warehouse Exclusive Brand new, Power by Power Supply, (not support charging), If you need the one with battery, you can have this one: B01LPXGZMM Fast Safe Extremely easy, High Lumens Egg Candler Cool light ! Long Electric Cable with American Plug, Very Durable with easy on and off button FUNTION: This candle Light will let you see the fertilized eggs by showing a dark spot and veins at the beginning, The candle light was very helpful and was really fun to watch the growth of the fertilized eggs. You can check about once or twice a week to make sure that they were still growing. The light candler tester is not just for someone who want to incubate eggs, it is also suitable for kids and students to learn the incubating process. Suitable for school funny class or shool laboratory.