This is a set of 15 books from the very popular "Which is Stronger!?" series. It's a great deal and highly recommended for families with children. ● Hippo vs. African Tigerfish ● Mantis vs. Scorpion ● Bee vs. Spider ● Beetle vs. Stag Beetle ● Shark vs. Swordfish ● Jellyfish vs. Electric Eel ● Bighorn Sheep vs. Bison ● Golden Eagle vs. Vulture ● Wolf vs. Hyena ● Whale vs. Giant Squid ● Snake vs. Crocodile ● Gorilla vs. Bear ● Lion vs. Tiger ● Elephant vs. Rhinoceros ● Elephant Seal vs. Polar Bear