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 What makes the Simba sheet special? How do I use my Simba Mattress Protector? Why should I choose a Simba Mattress Protector? What is the sheet made of? Can you take away my old mattress?