The 2 lb. bag of Zoo Med Creatures Sand is designed specifically for species of spider, insect or invertebrate that prefer to live in dry, desert-like environments. Made exclusively of all natural calcium carbonate, this substrate allows for your pets to engage in their natural burrowing behaviors without much difficulty. This allows the crawling critters to build shelters, hiding spots, exercise and function as they would inside their natural habitat. Depending on the needs of your pets, if you need to increase the level of humidity within the tank, pet owners should combine the Zoo Med Creatures Sand with the Zoo Med Creatures Eco Soil to create an environment with an increased amount of moisture.