Definitely moisture proof
Definitely moisture proof! The lid likes to snap shut too soon and I wish the top was slightly bigger. You see I'm not a big fan of salting my food, I bought this because I live in high humidity and my salt didn't do well in my old shakers. I use my shaker for scooping teaspoon measurements  but the hole is too small for my teaspoon so I have to resort to using my half tsp. Other than that awesome product.
Rating: 4 stars