4 Pack 4.5" Squeaky Dog Balls

My first purchase went well. All 4 balls squeaked well. I have two very strong and dedicated chewers - two very strong pitbulls who decimate toys. I didn't expect these to hold up for forever. For one of my dogs, the younger with less impulse control the ball lasted 25m which is 20m longer then the PetSmart ones so it was a win in my book. For my second older, has learned to cherish certain favored toys it lasted 2wks before the youngin' found it unattended lol. Another win! So I bought a second pack around 2 weeks later to have replacements handy. This time around 2 of thr 4 balls don't squeak. :-/ This is the major draw and fun of these balls for my dogs. So we're all disappointed. Not sure I'll try again. They're cheaper yes, but only if all 4 do what's promised. Otherwise I'd rather a couple dollars more of balls that are not defective.