It is very simple. It needs only 2 small batteries and it works 120h which is really great! There was 2 of those candles which is really great for this price. It came with (i am not sure which word to use but...) a thing that sticks near glass, ceramics and other stuff like that and it can float on the water. My mother was really happy about both gifts.
The only minus was that the blue color does not shine well as the red one. I do not know why. It came with the bad shape of the box (You could see in the pictures). I do not know why either why because it was packed well in the bigger box with other products which I bought. It was good that I was buying it for my mother, not for other people.
I add 2pictures - one with the red light and with a blue light. You will see some kind of the difference. I should add, that if You will really want that it will lighten Your bathroom - it won't. You will definitely need at least 2-4packs of them.