Memoi Spot on Basics cotton sweater tights are model SP-3405. These non-ribbed cotton tights are very economical. Great for school and to keep kids or ladies comfortable. Regarding sizing, they run a little bigger than some other brands. If a girl is just starting size 8-10 in Butterfly then she'd probably take a size 6 in the Memoi Spot on Basics. To get another idea of the sizing, I know that a girl/woman who is 5'4" and about 115 lbs. can fit comfortably into the size Average after they go into the dryer but that size can accommodate someone that weighs more. 75% cotton, 25% polyester, 2% spandex.
If you want baby sizes go to the Babies Section on the Website and scroll down to Baby Tights.
I have found the adult sizes Petite, Average, and Tall run a bit big in the foot. If you have a foot smaller than size 7 or 7 1/2 this product might be too big in the adult sizes. I haven't noticed this issue with the children's sizes.