Suitable for use on Oxygen concentrators up to 6L/min flow rate. Directions for use Fill the humidifier bottle with distilled water to the maximum fill line. Do not overfill. Attach the humidifier cap to the bottle. Tighten carefully making sure to thread the cap and bottle snugly. Avoid cross threading as this will cause a leak. Depending on the machine you have, attach the inlet nut to the oxygen outlet or humidifier adaptor on the oxygen system and hand tighten. Test the humidifier for leaks by setting the flow rate at 4 liters (or higher) and block the humidifier outlet. The safety valve should “pop” or “whistle” within 15 seconds. If it does not, check the bottle and lid to assure they are tight and repeat the test. After the humidifier bottle is attached properly, connect your cannula or mask tubing to the humidifier outlet, and turn the flow rate to your prescribed level. SECURE: The humidifier bottle features a secure cap when attached correctly. It ensures no leaks to allow for maximum function. PRESSURE RELIEF VALVE: The humidifier bottle features a pressure relief valve to allow control and limit of pressure for safety. COMPATIBILITY: The humidifier bottle can be attached with ease to most units of oxygen concentrator. Hassle free to use and attach. EASY TO USE AND CLEAN: This bottle comes with a clear set of step-by-step instructions on how to use and attach the product. It is also designed to be cleaned with ease.