Digital Watch, Square Digital Watch for Men and Women - Waterproof LED Watch with Big Numbers Dial, EL Backlight Luminous Display, Calendar Show, Simple and fashionablefor Students and Teens(Black)

I was looking for a watch that is less weight and numbers big to the whole watch size (one edge to the other edge) so that easily I can see the time without wearing spectacles. I am happy with this watch in these respects. I just got it delivered yesterday evening. But I have a major question:I dont know the battery life. Does it have replaceable battery option? (I assume yes, as the watch was not delivered with charger for recharging). Seller needs to answer this.