They are soft vs. hard plastic, flexible, can fit any size neck (it comes in 5 sizes) and, as she demonstrated on her Great Pyr, can be used on legs as well. It's just a very comfy, padded collar for dogs and cats. And since it's flexible your pet won't run into or and bounce off of walls or break anything while wearing it. The Great Pyr sleeps in his — that how used to it he is.
This article also has reviews from users and pictures of dogs actually wearing the cones.
They are sold locally by PetPeople, PetCo and Mutts & Co., to name a few, plus lots of online stores, including Amazon, carry them.