mh150 sunglasses from decathlon. Wayfarer shape but they fit my rather large head just fine and I liked the colours. They were cheap (£10) so it didn't matter so much if I lost or broke them. They were mirrored.
For about 6 years I relied on them and now I need to find a new brand or supplier.
I'm not in your shoes, but I gotta be honest, of all the useless jobs out there, firefighter is not one of them. I'm not trying to tell you you should find it fulfilling, simply that in my eyes at least, it's a worthy role.