It's another baking soda wheel. As Helloise sez: Baking soda a real workhorse around the house!
This one is specific to baby care. I imagine this is actually a really helpful wheel for new parents who are already on the baking soda bandwagon. You can ease insect bites and clean waterproof pants (remember those?) You can even send off to the company for leaflets.
This wheel is 6 and an eighth inches across and in very good shape. Alas, there is no date on it. It mentions cleaning soiled diapers, so that might be a clue.
Church & Dwight, the company that owns the Arm & Hammer brand, was formed in 1846. Their Specialty Brands division is the top producer of sodium bicarbonate in the U.S. Church & Dwight also makes animal nutrition products (love to see a wheel about that) and Trojan condoms. I'm sure Helloise owns some stock.