The Dishwasher Safe H4i Water Chamber Upgrade Kit for HumidAire 3i Heated Humidifiers is an upgrade kit for the S8 Series CPAP and VPAP machines that currently have the H3i Heated Humidifier. The H4i chamber now works in both the H3i and H4i humidifiers. It includes a dishwasher safe water chamber and a lid to convert H3i bodies into H4i-style humidifiers. The H4i humidifier has a larger chamber and heating plate to ensure humidification is optimal and available all night on one fill of the chamber.