The Voldyne 5000 Volumetric Exerciser is available through Amazon as well as several others at a very reasonable price.
There are others available from Amazon and the price is right.
And as already mentioned, most of the major pharmacies carry Incentive Spirometer device in their stores.
and Heart/Cardiovascular Disease.
"She Stood in the Storm & When the Wind Did Not Blow Her Away, She Adjusted Her Sails."