Our crawl space has vents all around the perimeter of the house. We want to keep these vents open to allow for air circulation in the crawl space. However, I've heard there are half-dome-shaped covers for the vents that reduce rain water, dust, etc. from entering the crawl space while still allowing for air circulation. Does anyone have a product they recommend for this? And where can I buy them? I tried to look on Lowe's and Home Depot, but could not find it.

We're in California in case that matters.

Thanks so much!