The “mini” version of our bestselling Simmons Sleepytime mattress is just the right size to fit your mini crib! The specially designed cover is waterproof and breathable. It repels water like vinyl without the off-gassing and vinyl odor. But unlike vinyl it breathes so that baby’s sleep surface never gets too hot. It’s durable and tear resistant too. The core is made from 100% recycled polyester fibers that are heat bonded vertically to provide a firm sleep surface as recommended by pediatricians. Between the fibers there are thousands of tiny air pockets that allow the core to breathe and air to flow through so that baby’s sleep environment always stays at a comfortable temperature. Simmons ultrasonic quilted waterproof protector will keep your mini mattress clean and fresh and helps keep dust mites out of your baby’s sleep environment. Made from 100% polyester it is strong and durable and will stand up to lots of washings. The absorbent layer will soak up all those little leaks and accidents. The non-toxic waterproof layer will ensure your mini mattress stays stain free for as long as you use it.