Make sure that you get the glass flask so you can get started as soon as possible. We've been searching for a proper diffuser stone or wooden block for a week, and it's just not worth the precious time. Plus, I'm sure that the flask will work very well. It's better to spend more on a better machine and better water ozonation system than to worry about whether or not you're doing your best for something serious like battling cancer.
Promolife sells a similar flask for a little bit less on their site, but we bought the one off of Longevity's site instead. It will be here on Thursday so we have yet to use or see it.
Make sure that the water is as cold as your husband can comfortably drink when you ozonate it (it does not have to be ice-cold, but cold nonetheless). Ozonate it for about 15 minutes and then drink it all within a minute or two after that. The faster he drinks it, the better it is.
Maybe James can comment further when he has the chance.