These small round gable vents are aluminum but you may try to compare them to a vinyl vent. Aluminum does cost more but for a hard to reach round gable vent, you might not want to replace it again in 2 years. That is the average lifetime of a vinyl or plastic gable vent. Only 2 years. These aluminum gable vents will last a lifetime.
Available in white primed aluminum only unless ordering in bulk quantity. All gable vents are manufactured 1/2 inch smaller than order measure. Order by opening size.