Pneumatically balanced, user-adjustable second stage. This pneumatically balanced, adjustable second stage is sure to provide you the highest performance for many years. The pneumatically balanced second stage provides the lowest possible inhalation effort. The second stage adjustment allows you to adjust your breathing effort, fine-tuning the regulator to your desired setting throughout your dive.

The venturi assist deflector vane directs airflow from the valve directly to the mouthpiece producing a smooth "venturi assisted" inhalation. Turning the venturi assist down, to a pre-dive position, prevents regulator free-flow while on the surface.

• Pneumatically balanced
• Diver-adjustable inhalation effort
• Adjustable venturi switch
• Nitrox compatible to 40%
• Paired with your choice of the new AT400 Over-Balanced Diaphragm First Stage featuring DVT (Dry Valve Technology)

AT400 First Stage
High performance over-balanced diaphragm first stage with environmental seal and the added protection of DVT (Dry Valve Technology).

• 4 LP ports, 2 HP ports for maximum hose placement
• DVT eliminates corrosion of critical internal components, bacteria, hose deterioration, and damaged gauges and computers
• Nitrox compatible to 40%

DVT (Dry Valve Technology)
A patented design that puts an end to flooded regulators without sacrificing performance! DVT is a revolutionary regulator technology designed to automatically prevent moisture and contaminants from entering your first stage, even if the dust cap is left off.

Pneumatically balanced valve design
A common objection to typical 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, the AT400 Pro features a pneumatically balanced valve that maintains a preferred breathing resistance throughout the dive. Set it once and the AT400 Pro automatically adjusts to make breathing as easy at 100 feet as it is at 30 feet - with no additional manual adjustment.

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 AT400 Pro's 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.

Adjustable venturi switch
The adjustable deflector vane found in the AT400 Pro diverts airflow from the valve directly to the mouthpiece, producing smooth venturi-assisted inhalation. With the addition of a user-adjustable venturi system, full adjustment control rests in the hands of the diver.

Computer optimized design
AERIS regulators are exclusively 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 AT400 Pro's unique deflector vane and housing design diverts airflow from the valve directly to the mouthpiece, producing smooth venturi-assisted inhalation.

Lightweight
The AT400 Pro's housing is made from an ABS/Polycarbonate composite blend of materials making the AT400 Pro both extremely rugged and lightweight (5.4 ounces) and nearly neutrally buoyant underwater, reducing jaw fatigue on extended dives. The extremely ligweight cover ring is machined from a solid piece of aircraft aluminum, and then hard anodized, utilizing a unique process to prevent corrosion.

Patented orthodontic mouthpiece
To further reduce jaw fatigue, the AT400 Pro features a patented Orthodontic Mouthpiece, designed to accommodate the natural overbite of the human jaw.

Nitrox Compatibility
The AT400 Pro 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.

AERIS ADVANTAGE LIMITED LIFETIME REGULATOR PARTS REPLACEMENT PROGRAM
The AERIS ADVANTAGE Program provides free standard replacement parts for your AERIS regulator for as long as you own it and have it serviced annually. The program includes all AERIS first stages and second stages. Register your regulator online with AERIS, and you are automatically enrolled in the program. There is no additional charge for this program.