Aqualung LEG3ND MBS Dive Regulator

MBS combines the two adjustments most regulators keep separate — venturi (free-flow) control and inhalation effort — into a single knob. One turn tunes both at once, so instead of juggling a lever and a dial, you make one intuitive adjustment to dial in your breathing from easy surface handling to full-flow performance at depth.

It is built for it. The first stage is an over-balanced diaphragm with an integrated dry chamber that keeps the internals clean and dry, plus deep external ribs that create a large heat-exchange surface to help prevent ice forming, and the second stage has its own heat exchanger. It also includes Aqua Lung's ACD (Auto Closure Device), which seals the inlet the moment you remove the regulator from the tank, keeping water, silt, and corrosion out between dives.

Aqua Lung backs the LEG3ND with a limited lifetime warranty to the original owner, provided it was purchased from an authorized Aqua Lung dealer (we are one) and receives annual inspection/service by an authorized dealer — which also enrolls it in Aqua Lung's Free Parts for Life program. Keep up the yearly service and the parts for each overhaul are covered.

Follow the interval in your regulator's manual, since manufacturers commonly specify an annual inspection or a set number of dives and many warranties depend on it. A regulator is life-support equipment, so service belongs with a factory-trained technician rather than being attempted at home. Have it looked at sooner than scheduled if you notice increased breathing effort, free-flow, bubbles, or water in the second stage.

Make sure the dust cap is dry and firmly seated over the first-stage inlet before the regulator goes anywhere near water, because water inside the first stage is the leading cause of internal corrosion. Rinse in fresh water without pressing the purge button, since purging while depressurized can draw water back into the second stage. Shake out the water and hang it to dry with the hoses in wide, gentle loops rather than tight bends.

Regulators travel well and are usually best carried in hand luggage where they will not be crushed or lost. A regulator holds no gas of its own, so there is nothing inherently problematic about it on an aircraft, though the airline and security screeners always have the final say. Pack it dry with the dust cap in place, in a padded regulator bag or wrapped in soft gear.

Many modern regulators are supplied as suitable for nitrox mixes up to 40 percent oxygen, which is the widely used recreational industry standard, while anything above that requires dedicated oxygen-clean equipment and procedures. Confirm what your specific regulator's manual states, and follow your nitrox training and your fill station's requirements. Never assume a regulator is oxygen-service clean simply because it looks clean or is new.

A yoke (A-clamp) fitting clamps over the tank valve and is the most common connection across much of the recreational world, while a DIN fitting screws into the valve and is standard in much of Europe and in technical diving. DIN captures the o-ring inside the threads, which many divers consider more secure, but yoke is often what rental cylinders provide. Adapters exist in both directions, so check what is used where you dive before deciding.

The octopus is your backup second stage, carried so you can share air with a buddy who is out of gas, or breathe from it yourself if your primary fails or free-flows. It is normally on a longer, brightly colored hose so it is easy to find and hand over under stress. Secure it in the triangle between your chin and the bottom of your rib cage so it is instantly accessible and not dragging through sand or coral.

Store it fully dry, out of sunlight, with the dust cap in place and the hoses in wide loops rather than tightly coiled. Avoid hanging it by the second stages for long periods, which stresses the hose fittings; laying it flat in a padded bag or hanging it by the first stage is kinder. If it has sat unused for a long stretch, have it checked before your next trip rather than assuming it is ready to dive.

The LEG3ND is the cold-water diaphragm regulator with the simplest controls: an over-balanced first stage with an integrated dry chamber and deep external heat-exchange ribs, a second-stage heat exchanger, the ACD auto closure device, and MBS, which merges venturi and inhalation adjustment into one knob. It needs annual service by an authorized dealer, which also keeps its limited lifetime warranty and Free Parts for Life active. The Atomic B2 is a balanced-piston regulator with titanium second-stage internals shared with the T3, an optional environmental seal, about 2.5 lbs in yoke, a 2-year/300-dive service interval, and a lifetime warranty Atomic states is not contingent on proof of service. Cold water and free parts point to the LEG3ND; long service intervals and a titanium second stage point to the B2.

ACD stands for Auto Closure Device. The moment you take the regulator off the tank valve, it seals the first stage inlet automatically — no water, salt or silt gets inside between dives. That matters most in the messy moments most divers do not think about: the rinse tank, the boat deck and the gear bag, where corrosion actually starts.