The "features" section says: "some are vinyl covered and waterproof"
Is that by random selection or is there a way to choose that option?
The bags I received were the normal canvas type, which I consider quite appropriate and suitable for most indoor/ studio work. I really like the compact size and high density that the shot provides. I typically bring about 4 of them along on location shoots, and they are virtually always fully utilized. They work well on both C-stands and the less heavy duty portable stands, since they don't hang down as much as conventional sand bags.