I have had several of these.  I have changed the battery before, but I find it is just easier to get a new one.  Considering the price, getting a new one is no problem.  I am loyal to this watch because it is so useful.  It is digital and has a stopwatch, with is key for running.  It is water resistant - so I would not recommend swimming with it. However, I just leave it on the edge of the pool and that works fine for me.  One of the best features is the timer.  By just pushing a button a few times, you can time several different time intervals.  This is most useful for cooking when you have multiple dishes cooking.  Perhaps the best feature is the size.  The face is smaller than a quarter.  Most watches are huge and a pain to wear - but not this one.