Chuckit! Tennis Balls, medium, four per pack. Built for fetch rather than tennis: natural rubber with an extra-thick core, so they bounce higher than a sports-store ball and float instead of sinking. The orange and blue shows up in long grass and muddy water where a yellow ball disappears. No toxic glue and a felt that stands up to a determined chewer. Fits Chuckit! launchers in the matching size. 2.5 inches across, for dogs around 20 to 60 lbs.