Simple and waterproof. This is the second one I own. The first one I bought lasted just over 4 years before it stopped working. It was used daily and had plenty of time to swim. I'll swap the battery and see if it still works. But just in case I have one more! For the price it couldn't be better. ****I was able to take off the back of my 4 year old watch and change the battery. To my delight it worked again. To really test this, I wore it swimming a few times. Still good, so again. The best little clock!