Nice heavy watch! It boasts a 500 meter resistance depth. (I'm not so sure though) I've previously had one Identical, went to change the battery the threads on the back were galled and I played hell getting it off. After changing the battery and putting a little silicone grease on the threads I reassembled it. But I learned at midnight each night it would stop. Upon tapping it the following day it would restart only to repeat at midnight again.