This is an integrated secondary 2nd Stage (octopus), and BCD power inflator.  It allows you to combine the two items, and reduce the hoses/2nd stage from your regulator setup; to help improve streamlining.  It also features a built-in underwater/surface signaling device, similar to the Sub Alert Duo.  It includes a rubber inflator hose, to be fitted into your 1st stage low-pressure port (replacing your existing inflator hose). 

The Air 3 is compatible with most BCD, such as Aqua-Lung, Dacor, Oceanic, SeaQuest, TUSA, US Diver, XS Scuba and others.