It was a Zipper Mattress Cover, and at first I said to myself OH NO THIS WILL BE HARD TO PUT MEMORYFOAM MATTRESS INTO.  It was a King Size bed so I said YOU CAN DO THIS to myself. Wow! I did it and it is something I will do again and again for the way it fit on the bed and you hear no plastic sound at all and easy to care for. I love the protection it gives the Memory foam...Quality excellent!