TECH SPECS:

• Brand: Cressi.

• SKU / Part Number: HX793151 (DIN version) / HX793051 (Yoke/INT version)

• First Stage Type: Hyper-balanced Diaphragm with SC (Sealed Chamber) Dry Kit

• First Stage Body: Forged Marine-Grade Chrome-Plated Brass

• Ports: 2 High Pressure (HP 7/16-20 UNF) ports, 4 Low Pressure (LP 3/8-24 UNF) ports angled for hose routing

• Cold Water Rating: Certified to EN250A standards for cold-water immersion (<50°F} / <10°C)

• Second Stage Type: Pneumatically Balanced Demand Valve

• Second Stage Adjustments: Venturi Effect adjustment lever (Dive / Pre-Dive) + Manual Inhalation Effort Control Knob

• Mouthpiece: Anatomical hypoallergenic silicone mouthpiece with bite tabs

• Operating Pressure: Yoke 3300 PSI (230 bar) / DIN 4350 PSI (300 bar)

• Nitrox Compatibility: Factory compatible up to 40% O²out of the box

• Model: MC11-SC / Zen Pro.

• Product category: Scuba diving regulator.

• Product type: First-stage and second-stage regulator set.

• Product finish: Silver / Black.

• First stage: MC11-SC.

• Second stage: Zen Pro.

• Hose: Included.

• Intended users: Recreational scuba divers and appropriately trained cold-water divers.

• Product certification: EN 250:2014 cold-water certification.

• Country of manufacture: Italy.

First stage – MC11-SC

• Operating mechanism: Hyperbalanced diaphragm.

• Environmental protection: Sealed chamber.

• Body material: Brass.

• Exterior finish: Electroless nickel plating.

• Intermediate pressure calibration: Approximately 9.5–10 bar.

• DIN service pressure: 300 bar / 4,350 PSI.

• INT service pressure: 232 bar / 3,365 PSI.

• High-pressure ports: 2 × 7/16-inch UNF.

• Medium-pressure ports: 4 × 3/8-inch UNF.

• Port arrangement: T-shaped configuration.

• Filter: High-capacity conical filter.

• Removable nozzle: AISI 316 stainless steel.

• Pressure technology: Cressi PressureSync.

• Flow rate: Approximately 4,500 litres/minute.

• First-stage weight, DIN: Approximately 458g.

• First-stage weight, INT: Approximately 603g.

Second stage – Zen Pro

• Operating mechanism: Downstream system

• Venturi control: Adjustable.

• Body material: Thermoconductive technopolymer / thermoplastic neopolymer.

• Weight without hose: Approximately 149g.

• Radial pressure openings: Yes.

• Purge system: Large purge button.

• Exhaust system: Removable exhaust tee.

• Cover: Stainless-steel cover.

• Surface finish: Anti-scratch treatment.

• Retention system: Bayonet-type cap holder with security lock.

• Internal lever: Low-friction design.

• Thermal protection: Thermoconductive second-stage construction.

Complete regulator weight

• DIN version with hose: Approximately 750g.

• INT version with hose: Approximately 897g

Key Advantages

• Environmental Isolation (SC Kit): The Sealed Chamber prevents water, silt, mud, and ice crystals from contacting the main diaphragm or spring, eliminating internal freezing risks and protecting internal components from corrosion.

• Dual Adjustment Control: The second stage allows fine-tuning on the fly—stiffen inhalation resistance during deep dives or heavy currents, and adjust the Venturi lever to prevent free-flows during shore entries.

• Hyper-Balanced Delivery: Intermediate pressure increases at greater depths at a rate higher than ambient hydrostatic pressure, compensating for increased air density to deliver effortless breathing at deep recreational or technical limits.

• Optimal Hose Layout: Four low-pressure ports are angled symmetrically to route primary hoses, octopuses, and drysuit/BCD inflators cleanly without sharp bends or neck pulling.

Tips & Tricks for Maintenance, Use & Storage

Free-Flow Prevention During Entries

• Set the Venturi lever on the second stage to the "Pre-Dive" (-) position before entering the water, jumping off a boat, or walking through surf. This disrupts surface air vortexing and stops accidental free-flows. Switch it to "Dive" (+) once underwater.

Fine-Tuning Inhalation Resistance

• Turn the side adjustment knob counter-clockwise to soften inhalation effort for easy breathing on relaxed dives.

• Turn the knob clockwise when swimming into heavy currents or when scootering with a DPV to prevent ambient water pressure from forcing the valve open.

Post-Dive Rinsing Protocols

• Keep Dust Cap Sealed: Always dry and firmly lock the rubber dust cap over the first stage inlet filter before rinsing in fresh water.

• Do NOT Press the Purge Button: Never depress the second-stage purge button while the regulator is unpressurized and submerged in rinse water. Pressing the purge allows water to travel backward into the hose and first stage valve mechanism.

Annual Service & Storage

• Store the regulator unpressurized with hoses relaxed (avoid tight coils or kinked hose wraps).

• Have an authorized Cressi technician check the internal O-rings, seats, and intermediate pressure annually to maintain EN250 cold-water certification.