What is softer than a 1,000 thread-count cotton sheet? The 400 thread-count Bamboo Pillow Case - King Set of 2. Woven for luxury, softness, and extreme durability from 100% bamboo muslin. These pillow cases are cooler than non-bamboo fabrics and have thermal-regulating properties to help you be cooler in the summer and warmer in the winter. Bamboo also has odor and allergy-resistant properties and is an extremely renewable source.