These are my favorite tea lights by far! They come ready to use, with the batteries pre-installed and use, what looks like, a normal watch battery that can be bought just about anywhere. I haven't had to change out the battery just yet though, as they seem to have a long life span. I have kept them on for hours with no hint of them being close to running out of battery! Unlike some of the other tea lights I have seen, the "flame is made of a softer rubber-esque material that has a curve to it, that makes it look more like an actual flame. With bright candle-like light, you only need one or two to light up a whole room with a warm flickering glow you would expect from a real candle. I am very happy with this candle and am sure to use them year round!