An oxygen concentrator is configured to provide oxygen at either lower pressures or higher pressures. When providing low pressure oxygen, the disclosed oxygen concentrator may be used with a conventional, low pressure oxygen delivery device, such as an oxygen cannula or mask, that is configured to deliver oxygen at approximate source pressures of 5 psig to 8 psig. When providing high pressure oxygen, the disclosed oxygen concentrator may be used with a high pressure oxygen delivery device, such as a low profile nasal cannula, that is configured to deliver oxygen at higher pressures. The disclosed oxygen concentrator is configured to automatically select whether low pressure oxygen or high pressure oxygen should be output to the user based on the type of connector used to couple a delivery device thereto, or based on characteristics of the delivery device itself.