The Philips Respironics DreamStation Heated Humidifier is the add-on humidifier for the original DreamStation series (DreamStation CPAP, Auto CPAP, and BiPAP models). It attaches to the machine and adds moisture to your therapy air to help reduce dry mouth, throat, and nasal irritation. It uses a 325 mL (11 oz) water chamber and works with standard, slim, and DreamStation heated tubing. A heated tube (sold separately) helps keep the air warm and reduce rainout. This is the humidifier for the first-generation DreamStation, not the DreamStation 2, which has its own built-in humidifier. Compatible only with Philips Respironics DreamStation series machines. Browse all CPAP humidifiers, and learn how to prevent rainout.