Single Zone Ductless products are perfect for heating and cooling a single room. Single zone simply means you have a single outside condenser and a single inside unit. They can be installed in smaller to medium size properties near the top of a stair case that will allow the air discharged from the unit to reach both the main and upstairs floor. Although this is not the most ideal solution, this kind of application does work and will help achieve increased indoor comfort at a lower price point than a more complex multi-zone system.