Transparent for maximum clarity, our latex-free AirLife empty humidifiers provide an economical alternative to prefilled humidifiers.These 370 mL capacity units have an audible-alarm pressure-relief valve to warn patient and caregivers of obstructions to flow. Available with either a 3 or 6 psi pressure-relief valve. The 6 psi model is designed for applications where longer lengths of tubing can increase back pressure. With both the jar and lid constructed of break-resistant plastic, humidifiers also feature an ergonomically designed, durable plastic flowmeter nut.