RE: where did cathe buy that ball used in the Intensity...
Kellye,
Sorry, I just saw your post, I have been ogne for a few weeks. I can't remember which particular ball I got - but I am sure from spri they are all good plastic.
The ball is a MAXATE resist-a-ball 1-800-926-6225. Some of the ones you can buy in the store have cheaper plasitc, so when you sit on it, you sink way down and it is much harder to keep it in place. You can see right through the plastic.
The MAXATE ball I have is orange like Cathe's and very firm and much more stable.
I hope this helps - it makes a huge difference in keeping your form.
Cheryl