Hollis Prism 2 Tek Closed Circuit Rebreather

A Review

Hollis Prism 2 Tek Closed Circuit Rebreather Review


Unlike many of the closed circuit rebreather available on the market today, the Prism 2 Tek provides users with the choice of electronically or manually controlling it which makes it highly user-friendly and very ergonomically balanced. As a closed circuit rebreather, the Prism 2 Tek is well fitted for deep diving, open water exploration, deep underwater caves and wreckage sites. In our Hollis Prism 2 Tek CCR review, we discuss the functionalities and features that it delivers while still touching on the specs, pros, and cons too.

The Prism 2 comes with shoulder-mounted and a back-mounted radial scrubber. This positioning is precisely placed to provide the easiest breathing experience for divers while offering very low resistive effort and much lower hydrostatic loading. The kit contains an electronic secondary control with primary LED display, a backplate/wing assembly providing a ready-to-use kit for divers who purchase it.

Designed with high-grade technology, the Prism 2 Tek offers divers a comfortably warm breathing experience in an optimal breathing mix at any depth. With this, you get an extended no-decompression times which allows you to take advantage of it more efficient gas use. That is where perfection meets precision.

For a better and uninhibited management of the Hollis Prism 2 Tek the 9V alkaline battery is positioned outside the breathing loop, so it does not commit any hindrance to the free movement and maneuvering of the scuba diver while underwater. Boasting of some 40 hours use time in 70F water temperature; it can well be said to be among the best optimally timed the durable battery in the rebreather list.

Hollis Prism 2 Tek CCR Review

Further on the scrubber, the Prism 2 Tek has a scrubber basket that is entirely better and more optimized upgrade of the old one. It comes in a canister that is way more efficient in all regards when compared to the old foam one. As for the hose, they are placed in a secured position that is also very easy to reach for divers in the case you need to assemble or dissemble it at any time.

The counterlungs are made of robust cordura materials that make the Hollis Prism 2 last longer regardless of the frequency of usage. As for the weight pocket of this awesome rebreather, they are well positioned for easier access while also being optimized for a quicker releasing experience. Given our comparison to the Prism Topaz, the weight system of the Prism 2 Tek is far better and well-improved than the zipper and bag system the Topaz comes with. As a feature of the improvement, the weight pockets of the Prism 2 gives more negative buoyancy.

The whole system is connected to a shearwater computer that acts as the secondary. I loved the computer and the capability. It calibrated the system and allows major changes during the dive. Having the unit and computer integrated is a definite plus as having all diving and rebreather information in one place is convenient.

The battery compartment of this rebreather is sealed with double O Rings and subsequently protected from knocks by a metal frame. This gives a guarantee of a safer and more prolonged battery life that aids your dive experience. The pressure relief valve positioned at the top of the unit is also well fitted to handle an increase in pressure at any time.  For easier reach, the on and off switch of the Prism 2 is located at the back of the head and protected by the cover plate. The switch button also doubles to calibrate the heads down display. The Prism 2 Tek has it oxygen tank positioned on the divers’ right side while the diluent is situated on the left.

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Counterlung Over-The-Shoulder
Weight System Integrated Weight Harness
Scrubber Flow Design Radial
Scrubber Duration 245 Mins
Battery Type 9 Volts Alkaline /3.6V Lithium Cell
Battery Life 40 Hours
Handset Shearwater Petrel (powered by Lithium Cell)
Sensor Life 12 Month in Air or 100 Dive Time
Weight 47 lbs. (inclusive of tanks)


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  • Shoulder mounted counterlungs provide easy breathing with low hydrostatic loading
  • Lowest Work of Breathing in industry at 0.94 J/L – Tested at 100M by ANSTI
  • Unit weight when fully charged, in standard configuration – approx. 47lbs
  • 3.5 Liter split counterlungs allows inhale and exhale counterlungs for high work loads
  • Counterlung drains make it easy to remove water during a dive
  • All gas lines external to the breathing loop prevents leaks from affecting the PPO2
  • Automatic diluent addition valve adds diluent during descent or when the loop volume is low
  • Manual diluent addition valve adds on board or off board diluent for loop flushing
  • Gases – Air, Trimix, and Heliox
  • Manual oxygen addition valve allows for manually controlling oxygen PPO2
  • High-performance open circuit Bail Out Valve option
  • Integral harness and BC or Backplate standard makes the Prism 2 ready to dive out of the box
  • Full range of wings/harness gives the ultimate customization
  • Accepts 13, 19, or 30 cu.ft. cylinders for flexible gas management
  • Eye level LED Primary display provides easy for monitoring system status
  • Displays PPO2 for each oxygen sensor is used to control PPO2 manually & assure electronics system is nominal
  • External power switch is easy to power on
  • Easy calibration with a push button O2 calibration
  • Large OLED Secondary Display is easy to read, even for your buddy
  • PPO2 Monitoring of Three Sensors Continuous display of each sensor’s PPO2, mv reading easy to access
  • Closed Circuit & Open Circuit, 5 gases supports diluent switching & Multi-gas mix dive plans
  • 2 button push OC bailout – If you have to leave the loop, quickly switches to bailout support
  • CNS Tracking based on real time oxygen exposure
  • Software Update via the web
  • Dive Log download and software updates via Bluetooth

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Pros and Cons

  • Possesses Automatic Diluent Valves
  • Possesses Manual Oxygen Additional Valve
  • Ready-To-Dive Out Of The Box
  • Full Range Wing / Harness
  • Eye Level Primary LED Display

  • Shuts Down Sensor Control As Well As Head Down Display


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Editors’ Opinion

As a closed circuit rebreather, the Hollis Prism 2 Tek is well fitted for deep diving, open water exploration, deep underwater caves and wreckage sites. This makes it a choice option for divers who do multi-dimensional dives.

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