HaVACo Quick Connect 12" Round Magnetic Grille with Metal Ring and Screw Pack with Anchors, ABS Plastic Ceiling Diffuser for Air Vent, Covers up to an 8" Opening, Home Improvement, White

I wish this were described better because I like the product its just not the right size. The outside diameter of the cover IS 12inches, BUT the metal mounting ring is only 8 inches. So the ring fits inside the vent hole, and is not even big enough to cover the 10 in opening.

Perfect and hard to find!

12" diameter, not for a 12" vent.