ULTIMATE SOFT & BREATHABLE: Mattress topper king with 110gsm 100% cotton, and the back is made of 85gsm 100% polyester virgin fiber padding makes the mattress topper super fluffy with breathable circulation inside, which is more breathable and softer than ordinary king mattress topper. The cotton fabric increases the mattress topper's air permeability, so this mattress pad will improve your sleep quality and let you have a good night.