These are new sandals that are missing the UGG box. There is a red mark on the insole heel to prevent in-store returns.
They are big kid's sizes:
The kid's size 3 fits the same as a women's US size 5
The kid's size 4 fits the same as a women's US size 6
The kid's size 5 fits the same as a women's US size 7
The kid's size 6 fits the same as a women's US size 8