Nothing beats a good old game of ball. Basketball that is! 
These balls are bouncy, strong and come in 3 sizes, so there's no option not to play.
 
BEST BITS:
Filled solid inner
Great for playing fetch with
SMALL
MEDIUM
LARGE 
Diameter: 5cm
Diameter: 6.5cm
Diameter: 8cm
For reference, the medium size is the size of a normal tennis ball.