What is the protector made of? Simba - Odyssey March 29, 2018 03:42 Updated Follow Our Mattress Protector uses the perfect combination of 100% polyurethane and 100% cotton. Related articles Why should I choose a Simba Mattress Protector? What size packaging does it come in and how heavy is the box? Can I buy the protector in John Lewis? How do I use my Simba Mattress Protector? What sizes do you offer and will this fit other mattresses too?