Dozen so can replace every month
Dozen so you can change monthly
I ordered 24. Mine just came all in one shipping box with no individual wrapping.
It's up to you. In a pristine house it could last 3 months. In my house, 10 days. Hahaha! Dirt and pets affect longevity.
Hi Yesser, either direction is fine. ~ Meghan, True Blue
No, it's the same on both sides.
Air flow is out of the room into the vent. You may feel a pulling sensation as you move closer to the opening if the unit is on.
I think both sides are the same.