What 3 Tools could you not survive without?

As an engineer who works in the field I am sure you have your favourite tools.

Some of the tools you are using will be very specialised for the technologies that you support.

But other tools will be your pride and joy. Tools that you use at home, in the car, at work, everywhere.

I’m interested in knowing what 3 tools you would choose if you couldn’t have any others.

(I was going to let you choose five tools, but the answers would be too long).

Please give a brief explanation of what makes each one of them so special for you.

Multitool – light and dependable

To be clear this has to be something physical, so no answers like, ingenuity, intelligence, and lateral thinking.

I’m hoping to get some good ideas from you for my birthday present list!