My dogs get so excited when I pull these out! I put a little Peanut Butter in the grooves at one end and little in the center and it keeps them very occupied. I have had for about 6 months and they hold up pretty well. My dogs are aggressive chewers so they have bitten the edges off but don't seem to swallow the little pieces that do come off. Just thought I should mention that in case you have a dog that may swallow plastic pieces.
I got these for my dogs. My smaller pooch is not a fan, I'm thinking because they are too big for him. My larger dog (65lbs) loves them. They last forever and help keep his teeth healthy.