This is a pretty way to store your coffee. I'm sure it vents the C02 as advertised, however, if you open it everyday like I do, then you will take out coffee and add more and more air every time you brew. Unlike a bag of coffee, you can't compress the air out of this unit, so, as a result your coffee will taste stale after 10-14 days. Additionally, you can pop off the valves easily on most coffee bags, so don't waste your money on buying Friis valves. Simply put your coffee in the can, peel off the new valve from the bag it came with, insert into top of new can and viola, no more buying valves.
If there were a way to vacuum the air out of the can, this thing would be perfect.