What material can this be used with?
This vent is specifically for drywall / gypsum wall and ceiling surfaces.

My drywall is already installed, can I use this?
Yes, absolutely!

Can this be used as an air return?
Yes it can!

Can this be used with retrofit ventilation fans?
Yes! In fact, this can ONLY be used with retrofit ventilation fans.

Are there restrictions of which ventilation fans I can use?
Yes, they can only be used with retrofit fans (that have a lip) that require a drywall opening between 8"x 8" to 10 1/2"x 10 1/2".