The Chuckit Fetch Medley contains 3 different balls with different fun features. Each pack contains a glow in the dark ball for evening walks, a ball that whistles as it flies through the air, and a super bouncy ball made with recycled rubber. All of the balls are compatible with the respective Chuckit Launchers (medium balls with the medium launcher, small balls with the small launcher). Key features 3 different types of ball to entertain your dog Medium balls measure 6. 5cm, small balls measure 4. 8cm Compatible with the respective Chuckit launchers.