What is the oldest piece of working tech you still use regularly?

[uptrendfinancialsignal]

To be honest here, when I looked at some of my old gadgets, I just burst out laughing. But funny enough, the oldest tech I still use daily is one small MP3 player that I actually bought when I was in the uni. That little thing has really suffered. It has fallen in water and there was a time I mistakenly left it inside the refrigerator.