Loose, naturalistic substrates have many benefits for exotic pets. As well as encouraging the natural digging instincts that many animals have, it also holds humidity and heat well. If you want to have live plants in your enclosure, it's good for that, too!
Zoo Med Creatures™ Sand is a small, 2 lb bag of calcium carbonate substrate. Use with desert species of tarantulas, scorpions, and other invertebrates for best results.