Ty Mini Boos Collectibles are small, hand-painted figurines. There are 13 Mini Boos in the fall 2018 release that is called "Series 3."
The boxes containing the Mini Boos are taped shut and each Mini Boo is enclosed (inside the box) in a sealed, opaque plastic bag so even when the box is open, the contents remain a mystery until the plastic bag is also opened.
There is a Mini Boos checklist included in every box. The checklist refers to 12 Mini Boos plus a "Rare Mystery Chaser."