Box sheet cover, waterproof (top surface only) Ivory, Single Purchased July 2025 *Waterproof on the top surface only; sides are not waterproof. I am currently using one of the two I purchased, and the fourth photo shows the underside. I am selling the unopened, unused one. The waterproof top surface is smooth and effectively waterproof. I use it on a 9cm thick mattress, but I think it will fit mattresses thicker than that as well. Please refrain from comments asking for a price reduction. m(__)m