Zeagle Onyx II Octo
In stock — ships from Irvine, CA
This item is currently on backorder. Order now to reserve yours, and we will ship it as soon as it is back in stock.
Zeagle Onyx II Octo is backordered and will ship as soon as it is back in stock.
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Product Information
The Zeagle Onyx II Octo is a lightweight, compact octopus second stage built on the design of the original Onyx Octo, with adjustable inhalation resistance, venturi free-flow control and an anti-freezing heat sink. It ships on a 36 inch (91.4 cm) hose with standard 3/8 inch threads, so it integrates with common regulator setups as a dedicated backup air source.
Who it is for
This is the alternate second stage for recreational and travel divers who want a compact, low-profile backup with adjustable inhalation resistance. The pneumatically balanced downstream valve and diver-adjustable inhalation resistance make it comfortable to donate in an out-of-gas situation, while the anodized aluminum heat sink supports performance in cooler water. Its compact, low-profile size and light weight keep the backup stage out of the way.
Key details
- Pneumatically balanced downstream valve for smooth airflow
- Venturi lever for free-flow control, plus adjustable inhalation resistance
- Anodized aluminum heat sink for anti-freezing performance
- TPU cover and Nylon 12 case with a 316 stainless steel poppet seat insert and silicone overmold
- Nitrile O-rings, elastomeric polymer diaphragm and silicone exhaust valve
- Ergonomic silicone rubber mouthpiece that reduces jaw fatigue
- 36 inch (91.4 cm) hose with 3/8 inch thread size
Compatibility and sizing
The included hose uses a 3/8 inch thread size and its 36 inch (91.4 cm) length suits use as a backup second stage. Zeagle backs the Onyx II Octo with a limited lifetime warranty to the original purchaser against defects in materials and workmanship, with annual servicing required; filters, hoses, O-rings, diaphragms and mouthpieces are warranted for two years.
DiveCatalog.com is an authorized Zeagle dealer and a real dive shop in Irvine, California since 2003. Call 888-701-4017 or start a chat if you want help confirming hose routing or first-stage compatibility before you order.
- Compact octopus second stage lightweight, low-profile design built on the DNA of the original Onyx Octo.
- Pneumatically balanced downstream valve delivers smooth airflow for a comfortable backup breathe.
- Venturi lever gives the diver precise free-flow control at the second stage.
- Adjustable inhalation resistance lets you tune breathing effort to conditions.
- Anti-freezing heat sink made from anodized aluminum supports performance in cooler water.
- Ergonomic silicone rubber mouthpiece designed to reduce jaw fatigue.
- 36 inch (91.4 cm) hose supplied with 3/8 inch threads for standard regulator setups.
- Durable case and cover TPU cover over a Nylon 12 case.
- 316 stainless steel poppet seat insert with silicone overmold for a reliable seal.
- Internals: nitrile O-rings, elastomeric polymer diaphragm and silicone exhaust valve.
- Limited lifetime warranty to the original purchaser against defects in materials and workmanship, annual servicing required.
| Product Type | Octopus (alternate second stage) |
| Valve Design | Pneumatically balanced downstream |
| Adjustments | Adjustable inhalation resistance, venturi free-flow lever |
| Cover | TPU |
| Case | Nylon 12 |
| Poppet Seat | 316 SS insert with silicone overmold |
| O-rings | Nitrile |
| Diaphragm | Elastomeric Polymer |
| Exhaust Valve | Silicone |
| Heat Sink | Anodized aluminum |
| Mouthpiece | Silicone rubber |
| Hose Length | 36" (91.4 cm) |
| Hose Thread Size | 3/8" |
| Warranty | Limited lifetime to original purchaser; filters, hoses, O-rings, diaphragms and mouthpieces two years |
| Service Requirement | Annual servicing required |
| MPN / SKU | 320-0310 |
⚠️ WARNING: This product contains chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.
Frequently Asked Questions
How often does a scuba regulator need servicing?
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.
How do I rinse and care for a regulator after diving?
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.
Can I fly with a scuba regulator?
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.
Can I use my regulator with nitrox?
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.
What is the difference between DIN and yoke regulators?
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.
What is the octopus regulator for?
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.
How should I store a regulator between dive trips?
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.
What hose comes with the Zeagle Onyx II Octo?
The Onyx II Octo comes with a 36 inch (91.4 cm) hose that uses a 3/8 inch thread size. Confirm your first stage has a free low-pressure port before installing.
Is the Zeagle Onyx II Octo a balanced second stage?
Yes. The Onyx II Octo uses a pneumatically balanced downstream valve, which helps keep airflow smooth and consistent. It also offers adjustable inhalation resistance and a venturi lever for free-flow control, so you can dial in breathing effort and reduce the chance of an unattended octopus free-flowing while it hangs in the water column.
Is the Onyx II Octo suitable for cold water diving?
Zeagle builds the Onyx II Octo with anti-freezing features, including an anodized aluminum heat sink. The venturi lever also lets you reduce free-flow tendency. As with any regulator, follow the guidance in your manual and your training agency's cold water procedures, and keep the unit on its required annual service schedule.
What warranty does Zeagle provide on the Onyx II Octo?
Zeagle provides a limited lifetime warranty to the original purchaser covering defects in materials and workmanship. Normal wear, accident damage and abuse are excluded, and annual servicing is required to keep coverage valid. Filters, hoses, O-rings, diaphragms and mouthpieces carry a two year warranty. Keep your service records, since warranty support depends on documented annual maintenance.












