The F8 1st stage has a dry-sealed spring chamber (to stop freezing at water temperatures below 40 degrees F). All delicate parts of the 1st stage including the main spring are sealed behind the clear hydrostatic diaphragm away from the effects of salt or other contaminants in the water, making it environmentally sealed. It is very low in profile, barely extending above the tank valve, and places the low pressure hoses directly out to the sides, in a pattern preferred by many divers.
This is very important in Octopus regulators, since the Pre-Dive position is much more resistant to Venturi-Free-flows that can sometimes result in significant air-loss during a dive. The F8 Octopus comes with a Lime cover and 36" hose.