Here's a dual wheel, presented by Mead's Dextri-Maltose. It was copyrighted in 1924 and is made of some sort of celluloid plastic, I guess. It measures 2.5 by 4.5 inches and is in excellent condition.
This gives recipes for feeding babies with milk, water, and the aforementioned Dextri-Maltose. You dial the baby's age and the weight associated with the average baby is shown. On the back, in very tiny text, are instructions and formulas for very young infants. There's even advice about giving cod liver oil. My father, born in 1920, told me his mother used to give him and his brother cod liver oil. I wonder if she had this wheel?
One thing I love about the back of this wheel is the advice given in case of diarrhea: "Write for Literature No. 109". AND FAST!