Canary Interactive IQ Treat Ball Dog Toy (Small 7.5cm) A fun pet ball to keep your dog mentally and physically stimulated! Step 1Put the crushed foods (neither too big nor too little) into the ball, your can directly put it though the yellow hole. Step 2: Show your pet that foods will fall out when the ball is rolling. He will be interested in it when he know the mystery. Helps keep dogs happy, healthy & fit Hollow center ideal for treats, peanut butter etc High-tech products, non compression voice, do not have to install the battery. The reason is that the internal magnetic field and a magnetic ball. When the dog eating and playing, the ball is rolling, and magnetic ball cutting magnetic line of force to generate electricity, which makes sound.