I had a box of dead watches I really liked, but with jewelers charging $25 up to change a battery, I figured this was worth a try.
I was able to fix 12 watches. Only 3 were beyond repair.

Before you start a project like this:  1) watch some of the online videos to see how it's done.  2) have a magnifier handy.  3) Have peace and quiet to focus on changing out very tiny batteries.

Most of my watches are inexpensive and have the pop off top so this had more than I needed. Otherwise it's got everything you need.