I have a black one, but it is a pretty big one. I put the peanut butter on the outside and then a little on the inside. He licked it for a little while and then left it alone the rest of the day. I had treats sticking out of it, he would get one out, eat it, then not bother with it anymore even when I showed him the other treats sticking out. If he has to work to do it, he's not interested Maybe I should get him a red one? I got the black because he's a chewer (loves rawhide and chewing on ropes, tears apart toys too).