One is better than two. Combine your alternate air source and BC inflator into one low profile, streamlined package. Purchase installed with a new BC or easily add to any Oceanic BC in minutes Compact, integrated design eliminates the bulk of a traditional octopus and hose No need to search in an emergency for an octo that is rarely used the Air XS 2 is always right where you need it Ergonomic design for ease of use Integrated pullball (COMPLETE UNIT ONLY) allows activation of the cable exhaust valve while using the Air XS 2