The soft unbleached 100% cotton percale cover and 100% wool fill are quilted together to eliminate shifting, clumping and hollow spots. Natura"s Cry Less wool has the exceptional ability to insulate against heat and cold, creating a natural climate zone that wicks away moisture before it has a chance to build up and disturb sleep. It is also naturally hypoallergenic, resisting the buildup of harmful allergens and promoting the healthy, sound sleep that"s so important for your baby"s early years. The best of all is that the cry less wool inside the mattress pad is fully washable, making it a naturally convenient choice for protecting your crib mattress.