Top-Fill Humidifiers are great for those who may have difficulty lifting or carrying removable water tanks to and from a sink or bathtub. Unlike most humidifiers that have a removable water tank which is filled at a sink or bathtub and then carried back onto the humidifier base, these humidifiers can be filled by pouring water directly into the humidifier, bypassing the need for a removable water tank. You can fill these humidifiers using any size water container of your choosing, large or small. Eliminating the need for a removable water tank also means that you do not have to worry about dropping (and possibly breaking) a water tank. These humidifiers are great for those with arthritis or anyone who is unable to lift or carry a full water tank.