Adjustable-opening treat ball - put your pet favorite kibble or small treat (diced carrot, or dried fruit or herbs) inside the hollow ball, adjust the opening to control flow of treats. Interactive treat - roll and push the treat ball, food falls out, thus encouraging more play. Three colors and two size - try different treats for your pets. Good boredom buster for guinea pigs, rabbits, rats, hedgehogs and other small pets. Keep your pet entertained for hours stimulating their mental and physical. Small size 2.8-inch/7cm diameter, Large size 3.9-inch/10cm diameter. Product description Size:Small | Color:Yellow & Green Niteangel Treat Ball is an adjustable-opening treat ball, that is a great boredom buster for guinea pigs, rabbits, rats, hedgehogs, and other small pets. Please supervise your pet when they are playing with these balls.