This demonstration video goes over the features of the Hollis 321 Octo. The 321 Octo has a pneumatically balanced second stage and an orthodontic mouthpiece. It is Nitrox compatible to 40% (the recreational limits of nitrox). The Octo comes in a bright "Hi-Viz" yellow hose and 2nd stage cover for easy identification. Includes a 36" Hi-Viz neon yellow hose.