I bought this to keep dust off my griddle since I keep it inside my shop. I LOVE the included plastic piece keeping it 'domed' up over the griddle.
I can't speak to waterproofness but it allows me to keep grill covered.
I like the bottom not touching the ground to not make a snake home (I live in southeast Texas).
The material appears to be the same quality of my outdoor cover on my grill.
The corners are reinforced. I like it!!