These mattresses are called "Airflow" and are made from breathable fibre: no sweat! Despite their lower price point these guest beds are extremely comfortoble, in fact it's not uncommon for our customers to like them better than other more expensive beds that we have. The Value beds are the only ones without castors, all others have castors. Even though all Airflow mattresses look identical they do in fact differ in thickness: Value is the thinnest, Advance is thicker, and Revolution & Supreme are thickest. We recommend using Value beds only for occasional sleep, other models do have a considerably better mattress, incl. the Advance bed. Value beds take up less space when folded and are a lot lighter. Airflow mattress covers are not removable but the mattress surface can we easily cleaned and dries quickly.