There is no second adult to check with at two in the morning. Nobody who already knows whether that noise is normal, whether the room is too warm, or whether this is the sort of thing you are supposed to worry about. All the things other parents seemed to simply know, I had to work out on my own, usually at the worst hour, usually while holding her.

What I noticed, once I had been doing it a while, is that most of it was not really fear. It was distance. She was in another room and I was awake. She was in the back of the car and I was in the front. Either way I could not see her, and the only way to know anything was to get up and go and look. So I got up and went and looked, all night, for months.

Babi came out of that. Not from a business plan and not from a statistic. From wanting the answer to the same small question, over and over, without opening a door to get it.

So we made two things. One for the car, because a quiet car and an empty one look the same from the front seat. One for the cot, because eleven hours is a long time to guess.

Neither of them protects her. What they do is shorten the gap between something changing and me knowing about it, so I can go and see for myself.

That is the whole product. Not protection, and not certainty. Attention, handed to you sooner than you would have gathered it yourself.