Got this for my almost four year old, takes a bit but she can open it in the end. Enough for a toast sandwich and something small on the side.
Bought a medium sized "fridge to go" lunch bag from Biome (Australian) too which it fits into that keeps food cold up to 8h so you know you can put cut food in this lunchbox and not worry about food poisoning after an hour.
I really wanted to love this lunchbox because it's nontoxic steel and reusable, but the one issue I have with this lunchbox is the company states the following: "washing is a total breeze with no little crevices or fixed seals to harbour yucky surprises" which is false, because the outer rim/edge of it has a crevice all around the lunchbox. Why on earth would they not seal that and then state there are no crevices?
If my daughter spills anything liquid across the lunchbox and onto any direction of that rim it's going in that little opening/crevice, and let me tell you it's impossible to clean. No tiny brush in this world will get in there. I've attached a photo with red arrows pointing to the crevices around the rim. In that regard it was a waste of money to be honest because that will undoubtedly harbour mould and bacteria eventually and it's a very pricey lunchbox. I won't be buying Nestling lunchboxes anymore unfortunately purely because of this. They're also a bit heavy for a child.