Ziplok
Just a suggestion for another time, as I see you’ve ordered some sugar free sachets, Shinamae (I hadn’t realised from your first post that you wanted them for work), but could you measure out enough oats the night before into a microwaveable container (you can get some that look like mugs) and then add your milk/water once you’re ready to eat them and pop them in the microwave at work for a few minutes on high? It might work out less expensive than buying the sachets.
That's what I was wondering about too.
I don't eat porridge very often because it spikes my blood glucose, but when I do, I put 40g of plain oats with milk and cinnamon in the microwave.
Shiname Presumably you have access to milk/water at work, so why don't you just use oats from a big packet?