Pneumatically Balanced Valve.
The pneumatically balanced second stage reduces breathing resistance to near zero with a balanced valve seat designed to respond to the slightest inhalation.
 A pneumatically balanced second stage actually has (or can have) the same initial crack opening effort as a mechanically balanced, but the spring force of a pneumatically balanced second stage is lighter so it’s spring rate is also lower. Therefore the force required to open the valve farther as flow increases is less than that required for a mechanically balanced second stage with a higher rate spring. So the total effort to breathe the pneumatically balanced second stage is indeed less. The spring force must be just enough to overcome the difference between downstream air pressure and upstream balance chamber pressure. The downstream air travels through a hole in the poppet into the balance chamber and applies an "upstream" force just slightly less than the downstream force. Diver Adjustable Inhalation Effort.
Most downstream demand valve regulators are calibrated during manufacturing to a single, 'middle of the road' operation. Whether finning up current at 100+ feet or merely snorkeling out to the dive site, this factory adjustment may not be optimum for the wide variety of demands we place on our equipment. A simple twist of the adjustment knob enables complete control... Set the inhalation requirement to near zero when you need ultimate performance, or tune it for greater resistance as conditions or preferences change.  Patented Dynamic Adjustment.
A common objection to adjustable second stages is that divers can't imagine themselves twisting and turning a knob as they descend and ascend through the depths. If inhalation resistance is set near zero at depth, your ascent would require you to manually increase resistance as ambient water pressure is reduced to prevent free-flow. Taking another stride beyond common second stage engineering, Oceanic designed a patented DYNAMIC ADJUSTMENT feature into the heart of the EOS. This mechanically balanced valve maintains your preferred breathing resistance throughout the dive. Set it once and the EOS automatically adjusts to make breathing as easy at 100 feet as it is at 30 feet - with no additional manual adjustment.
Ergonomic A.V.S. (Adjustable Venturi System) Dive/Pre-Dive Switch.
Designed to be unobtrusive, yet easily manipulated even with the thickest gloves, the A.V.S. deflector vane found in the EOS either diverts airflow from the valve to the mouthpiece, producing effortless venturi-assisted inhalation or creates enough resistance to prevent free flow on the surface. Stainless Steel Inline Swivel.
Ever notice that nearly every picture you see of a diver, their regulator looks like it’s not the least bit comfortable? The EOS features an ergonomically designed stainless steel (no plating) in-line swivel for ultimate comfort. Computer Optimized Design.
The EOS was designed using the latest 3-D computer modeling techniques. This allows us the ability to model and test performance while still in the early stages of development. The EOS’s unique valve, deflector vane and housing design directs airflow from the valve directly to the mouthpiece, producing nearly effortless venturi-assisted inhalation. Patented Orthodontic Mouthpiece with High-Density Bite Tabs.
To further reduce jaw fatigue, the EOS features a patented Orthodontic Mouthpiece, designed to accommodate the natural overbite of the human jaw. Nitrox Compatible.
The EOS | FDX-10 is classified as being suitable for use with Nitrox breathing gas mixtures containing up to 40% oxygen by volume without the need for special preparation, cleaning or component parts. FDX-10 Over-Balanced Diaphragm First Stage.
The Forged from marine-grade brass, the FDX-10 features optimized air paths and angled hose ports for superior performance and comfort. A sealed Balanced Diaphragm design, Enviro Kit and patented DVT (Dry Valve Technology) isolate all internal components from the environment. 2 high pressure and 4 low pressure ports allow convenient and comfortable hose routing. 
The FDX-10 high performance over-balanced first stage provides progressively greater intermediate pressure as depth and gas density increases. The center “pads” that the diaphragms act against are different sizes so the working area of the outer environmental diaphragm is larger than the working area of the inner diaphragm. As depth increases, more pressure is applied to the larger surface area of the outer diaphragm than would be applied to the internal diaphragm. The result is superior gas delivery under the most extreme conditions. DVT (Dry Valve Technology)
Ever wonder why they call it a "dust cap" and not a water cap? Most dust caps are not designed to keep water from entering your first stage. Regardless of how carefully you may maintain your regulator, water entry is a much more common problem than most divers realize. DVT is a revolutionary regulator technology designed to automatically eliminate moisture and contaminants from entering your first stage, even if the dust cap is accidentally left off. DVT eliminates corrosion of critical internal components, bacteria, hose deterioration, and damaged gauges and computers. 
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