These are the plain booties. The pink and purple are both the "medium size" which I would probably get for babies between 3 and 9 months. "Small" would be for newborn-3 mths, and "Large" would probably be for 9mth-12+mths. It always depends on the size of the child! The booties come in solid colors, or with contrasting soles, like the small-sized green/teal pair below. Only $5 each!