For a desktop (stationary) concentrator, 5L means a flow rate of 5 liters per minute. Take our 5L portable concentrator as an example: it actually delivers 1.0 L/min. Under the concept of equivalence, this is multiplied by 5 (1.0 × 5 = 5), making it equivalent to the 5 L/min output of a desktop unit. (The oxygen utilization rate of a desktop concentrator is approximately 19.999% — roughly 20% — and its breathing ratio is 1:5.)