Alternate Air Source: An Alternate Air Source is also called an "octopus" because this is attached to the SCUBA Regulator with an extra air hose which makes the regulator look like a multi-tentacled octopus! The Alternate Air Source is an additional regulator second stage that attaches to the regulator first stage. The Alternate Air Source is for required for diving safely. If another diver runs out of air they can come to you and breathe from this extra regulator to safely get back to the surface. Required Features Octopus Mouthpiece: The mouthpiece is the part of the octopus that we put in a diver puts in his mouth to breathe through. Octopus mouthpieces should be a standard size to fit any diver's mouth; not a custom mouthpiece. The idea is that any diver should be able to use the mouthpiece in an emergency without a problem. Octopus Purge Button: The purge button on the octopus is used to remove water that has entered the octopus before we breathe. Located on the front of the second stage, when pushed the purge button shoots air from the air hose into the octopus to exhaust any water inside the mouthpiece. AQUA LUNG® ABS Octopus Mr. and Mrs. Brown use the Aqua Lung® ABS Octopus because it is compact and they can easy tuck it inside their special BCs' octopus pockets for quick removal in an emergency. Special ABS Octopus Features Easy Breathing in Any Position: This alternate air source is designed to breathe easily whether a diver is right-side up or up-side down or the in right hand or left hand position. Compact Low Profile Design: The flattened compact design allows octopus to be easily worn and ready for use. Yellow High Visibility Ring: High visibility yellow ring on octopus body is easily spotted by a diver in case of an out-of-air emergency. Yellow High Visibilty Air Hose: High visibility yellow air hose is easily spotted by a diver in case of an out-of-air emergency and distinguishes octopus from the primary SCUBA Regulator. Extra Length Air Hose: Extra long 39 inch air hose makes it easier for an out-of-air diver to use the octopus that is attached to an air tank he is not wearing.