Ask HN: What are some really strong reasons for using a version control system?

I recently started working for a manufacturing company with a very small team of developers.

The team does not user version control and it's appalling to me. They either maintain the versions in their local machine or on a server.

I have been talking to my manager and trying to convince him to start using one.

What are some really strong reasons can I give him so that he realizes that we can't do without a version control.