When Babe Sleeps Better, Mom Sleeps Better! Our Snug Soft Imperial Crib Mattress Cover offers a natural solution to a better night's sleep. Made from 100% wool, this soft and comfortable mattress cover is resilient to body impressions and relieves pressure. Acting as a natural thermostat, it maintains the perfect sleep environment in every season. In the summer months, the wool absorbs moisture and sweat, keeping your sheets crisp and cool. In the winter, the wool acts an insulator, keeping you deliciously cozy and warm!