The lunch box and the insulated food jar, carried together. Cold food in one, something hot in the other, the office standard, and the pair that covers a whole day without a microwave anywhere in the story.
Both are 18/8 food-grade stainless steel, uncoated inside, leak-proof and dishwasher safe. The jar's outer lid is plastic. It has to grip and survive being dropped; everything your food touches is steel.
3-year warranty, and every part of both is available separately under spare parts. Both can be laser-engraved. See individual engraving.