Late August is the strange part of the year. The afternoons still ask for a cold drink. Some of the mornings have started to ask for a warm one. For about three weeks, both are true on the same day.
Most of what we own picks a side. A thermos is for winter. A fan is for July. The mini air cooler on the corner of the desk has been earning its keep since June, and it will keep earning it through September — but there is a morning coming, probably in the next few weeks, when nobody reaches for it.
The self-cooling and heating tumbler is the one thing here that doesn't have to pick.
It runs from −5°C to 55°C — 23°F to 131°F. That's iced water at two in the afternoon and warm coffee at seven in the morning, and one button moves between them. No second cup. No swapping anything out. The same object doing the opposite job, because the season asked.
It isn't a clever feature bolted on top. It's a semiconductor chip, and a semiconductor chip runs in both directions — cooling and heating are the same mechanism with the current reversed. That's simply what the physics does.
A few honest notes, since this is the week people start thinking about it:
The heating side is warm, not hot. Fifty-five degrees Celsius is comfortable-drinking temperature, not fresh off the kettle. If you want scalding coffee, this isn't the cup.
It charges over USB, which means the car and the desk both work, and the kitchen counter is not the only place it can live.
The interior is SUS316 food-grade stainless, so the coffee tastes like coffee in the morning and the water tastes like nothing in the afternoon. That matters more than it sounds when one cup is doing both jobs.
Here's the small ritual worth trying over the next few weeks, while the weather can't make up its mind. Fill it warm at the start of the day and let the morning have it. Rinse it at lunch, switch the button, and let the afternoon have it cold. One object, two seasons, about four seconds of effort in between.
Sometime in October the button will stop moving. It'll sit on warm and stay there until spring. That's fine — that's rather the point of a thing that can do both. You only notice it during the weeks when you'd otherwise need two.
The fan gets to rest soon. The tumbler just turns around.