Vintorio Replacement Pack for Vintorio Wine Aerator Pourer - Extra O-Rings and Air-tubes

We know that things happen, and it's easy to misplace a piece or two! So, we created a replacement set for our best-selling Vintorio Wine Aerator Pourer.  The replacement parts set include several extra replacement o-rings (rubber rings) and two extra stems (air tubes). What is the o-ring (clear rubber ring) for? The o-ring creates an airtight seal to prevent any leaks or spills. Every wine aerator pourer comes with a clear o-ring, but some people dislodge and misplace the o-ring during cleaning.