My cat Foutchie is heading toward 5 now and no one told her the trouble with a kitten is it eventually becomes a cat (so take that Ogden Nash!).  She still voom-voom-vooms around at a pace that makes me exhausted.  She loves toys, especially stuff she chases.  So the bubbles are great full.  Especially since they are catnip bubbles.  You don't have the worry about them getting soap on them and making them sick.  She love jumping high to pop them.