The Simmons OOPS waterproof ThermoCool mattress protector will help keep your crib mattress clean and fresh without adding bulk to baby’s bedding. “ThermoCool” technology uses specially engineered fibers that absorb excess heat to help keep baby cool while sleeping. The non-toxic waterproof layer will keep your mattress stain free and is dust mite resistant. Help extend the life of your mattress with the OOPS ThermoCool protector!