We have a 1/2 Aussie 1/2 English Setter who is 100% go all the time. He loves playing fetch and can do so for hours. The Chuckit is a life saver and these balls are great! They seem to be non-abrasive (certain "tennis" balls claim this but his teeth prove them wrong!) and have a great bounce and slight whistling sound. He likes the glow in the dark best! I like that they are lighter weight and softer than other rubber balls we have used. A definite hit!