Keep this small 4 cubic foot personal oxygen system within reach, for safety in the event of unexpected failure or depletion of your main oxygen supply, or unexpected cabin depressurization. This system is designed to give you oxygen based on a cabin pressure of 25,000 feet and will flow at this set rate for approximately 35 minutes, so that you can have time to get down to a safe altitude where you can breathe normally under the conditions. Simple to use, when needed pull the mask and don. The motion of pulling the mask pulls a cable that initiates the flow of oxygen. This system can be refilled after each use. This system comes standard with an aluminum DOT 3AL cylinder that has no life limits and requires a recertification each 5 years. The interface to the system is a standard economy rebreather mask, but can be upgraded to a TSO C103 mask or a TSO 64 type mask(please call for this option). The PRO2 emergency systems are available in 2, 4 or 6 cubic foot configurations, and the 4 or 6 cubic foot systems are available in single or dual user configurations.