A run of forty is small enough that one person can look at every piece before it ships, and large enough that the weavers are not working for nothing.
It is not a scarcity tactic. It is the number at which the making stays honest.
One pair of hands
Each garment is sewn start to finish by a single machinist rather than passed along a line. It is slower, and the finish is noticeably better for it.
When it is gone
We do not restock. The cost of that is selling out; the benefit is that we have never held a sale to clear stock we should not have made.
Made to last, in numbers small enough to mean it.