Chilly weather is upon us, so new flannel pajamas seem like a good idea. Though one-piece pajamas are common for children, I was a little surprised to see them offered for men. The option for short sleeves would indicate that some men wore these in summer. In this case, they'd be made of a light cotton fabric.
The little chart showing chest measurement and the corresponding neck measurement is helpful to have around, since some shirt patterns at this period give only the neck measurement.