To emphasize what has already been said, you do not need this product to perform the exercises. Pursed lips will to the same thing. This product is similar to the Powerlung that has been marketed to triathletes for about a decade.
First of all, all cardiovascular exercise conditions the muscles used in breathing and improves gas exchange efficiency. Respiratory resistance training seems to play a part to supplement a good cardiovascular exercise program, however. A recent review of the current literature can be accessed at
http://www.ncbi.nlm.nih.gov/entrez/...ve&db=pubmed&dopt=Abstract&list_uids=15162248. Note that increased lung volume is not even discussed in the abstract- only increased respiratory efficiency.
More information on this type of training can be found (albeit embedded in marketing) at
http://us.powerlung.com/en/. Note that all of the techniques described on the Powerlung website can be performed with nothing more than pursed lips. You do not need any type of contraption to provide the resistance, and I think this has been the general consensus from Powerlung owners who have commented to me.
As an aside, swim training in and of itself conditions the breathing muscles in a similar fashion. This is because the lungs are submerged while the mouth is at the surface. This difference in hydrostatic pressure is enough to trigger a conditioning response that increases respiratory efficiency moreso than other forms of exercise.
While swimmers do have average lung volumes greater than participants in other sports, no study has definitively determined if this is a training effect or a selection bias, meaning that people born with larger lung volumes gravitate towards swimming.
Cameron