I purchased a 3 pack of the Kong squeaky tennis balls for my Boxer/German Shepherd mix nearly a year ago. I am only now having to replace them due to them getting lost or wore out (think about it...a year for a tennis ball? Awesome!) My only "problem" stems from this: my dog loves the Kong squeaky tennis ball so much that he refuses to fetch with an ordinary tennis ball. He is spoiled, but considering his abused life before he came to our family, he's worth every bit of spoiling I can give him!
KONG® Air Dog® Tennis Ball Set Squeaker Dog Toy