I am in the process of changing out several single hung, aluminum frame windows in my house. The new windows have a sticker that says "Glazed with Breather Tubes." I suspect that they would be vented to the inside of the house so the cold outside air isn't getting between the panes. My question is this: Since I can't see any vent or tubing holes, how does this work? What precautions do I have to take when installing the windows to make sure I don't plug something with caulking/ stucco etc.? Appreciate any help, deecee.