SafeRest Crib Encasements Protects Against Fluids. Through extensive research and development, SafeRest has created a better way to protect your crib. Our encasements were specifically designed combining cutting edge Micro-Zippers along with breathable fabric. Rather than disposing of expensive unprotected crib mattress, SafeRest encasements seal and safeguard your mattress. To keep our encasements cool and noiseless, the surface material is made with soft cotton terry back coated with a breathable 100% waterproof membrane layer. It naturally absorbs moisture and is completely noiseless.