Tossed this across the yard expecting my lab to lose interest in ten minutes, but the ring's shape makes it roll unpredictably and she chased it for a solid half hour. The handle on the throwing stick saves my shoulder too, since I can launch it way farther than a ball by hand.
Took this to the park expecting my arm to give out before my shepherd did, but the rolling action does most of the work for me. The ring flies farther than a ball and she actually brings it back instead of playing keep-away.