The Hollis Prism 2 (P2) Rebreather

Hollis Prism 2 Rebreather

CE APPROVED Order Yours Now


Rebreathers UK are proud to be the appointed distributor for the Hollis Prism 2, a fully closed circuit Rebreather, ideal for exploring open ocean, caves, or wrecks. This unit can be electronically or manually controlled which means you choose how you want the loop PPO2 maintained.

The PRISM 2 is an electronically or manually controlled, constant PO2, modular, closed circuit diving system. CE approved to EN 14143:2013

Includes option for front-mounted or back-mounted counterlung. Combined with the rear mounted radial scrubber, the Hollis Prism 2 provides easy breathing with low resistive effort and low hydrostatic loading. The Hollis Prism 2 has also been tested by ANSTI at 100M and has the lowest WOB of any mixed gas CCR on the market. The standard kit includes an electronic secondary control and primary LED displays with a backplate/wing assembly that provides a complete kit ready to dive out of the box. Tanks and valves are purchased separately.

Breathing Loop

Its breathing loop which is a keyed
one-way assembly consists of a closeable mouthpiece assembly with mushroom
check valves on either side, which ensure uni-directional flow.

Prism 2 now includes the option of front mounted or backmounted counterlungs. Combined with the rear mounted radial scrubber, the Prism 2 provides easy breathing with low resistive effort and low hydrostatic loading.

These counter lungs are fitted with both automatic and manual gas addition systems and a variable volume control valve (only on FMCL version) that is used upon ascent to vent excess expanding gas volume or to purge the loop. Diluent addition is automatically achieved as hydrostatic pressure increases and the counter lung collapses against the valve actuator.

Hollis Prism 2 Front Mounted Counterlungs

Front Mounted Counterlungs

Dual, front mounted counterlungs provide the diver with a flexible reservoir equivalent to the maximum displacement of the diver’s own lung volume and ensures the lowest possible hydrostatic loading.

These counterlungs are fitted with both automatic and manual gas addition systems and a variable volume control valve (used upon ascent to vent excess expanding gas volume or to purge the loop). Diluent addition is automatically achieved as hydrostatic pressure increases and the counter lung collapses against the valve actuator.

Hollis Prism 2 Back Mounted Counterlungs

Back Mounted Counterlungs

Back Mounted counterlung positions lungs behind the diver leaving the chest free for attachment of additional tanks and accessories. This also allows improved streamlining with less drag and better horizontal trim.

Features a 2 piece bag design for improved WOB performance and easy removal of the internal lung for cleaning or replacement. ADV Upstream Valve design is reliable and resistant to free flow which is a benefit for the addition of valuable diluent gas. All gas delivery systems on the Prism 2 have both automatic and manual function. Water Trapping T-pieces keep excess water from the breathing loop inside the counterlung for easy draining. Streamlined Hose Fittings keep LP hoses routed inside closest to the diver which avoids overhead interference. Machined DIL and O2 MAV controls ensure a rugged and reliable design, also allowing offboard gas plugin on both sides.
Hollis Prism 2 Radial Scrubber

Rear Mounted Radial Scrubber

The Prism 2 utilizes a user packed, radial 5.5lb CO2 scrubber, which features the best possible duration, insulation and work of breathing on the rebreather. The scrubber canister is mounted vertically on the backplate and between twin supply cylinders (one each, oxygen and diluent).

The clear scrubber bucket is molded from Engineered Thermoplastic. This Hollis exclusive design ensures the CO2 scrubber is installed, packed and provides a visual for positive loop integrity.

Hollis Prism 2 DSV and BOV

High Performance DSV and BOV

Every Hollis Prism 2 ships complete with a DSV (Dive Surface Valve) standard and BOV (Bailout Valve) as an available option. The BOV features a high performance regulator valve, is incredibly lightweight and is a direct bolt on for your Prism 2 to replace the DSV. The Prism 2 BOV is considered a basic safety device for the rebreather by many professionals and meets the requirements for training in Technical rebreather courses



With the electronics switched on, the secondary also provides a status check for the battery and displays the set point selected for the dive along with other critical information. The electronics vote between the three proprietary galvanic sensors and control the operation of a low wattage solenoid valve on the oxygen supply.

Prism 2 now supports the latest in oxygen sensor technology featuring:

  • Warn for use of sensor past expiry date
  • Advance warning for sensor ordering/replacement
  • Check proper sensor model/type
  • Provide date of last calibration

Primary Display

Hollis Prism 2 Heads Up Display

Heads Up Display (HUD)

The Primary Display (HUD) consists of 3 bicolor (red/green) LEDs mounted on either the right or left side of the DSV/BOV mouthpiece just below eye level. Each LED provides a status indicator for its corresponding O2 sensor by using a "Smithers Code" flashing the status on a cycling 5-second loop during the dive.


Secondary Display

Hollis Prism 2 Computer


The Shearwater Petrel is the computer display on the Prism 2 and was chosen for this application as it is one of the most advanced mixed gas CCR computers available today. The Petrel is designed to control the Prism 2 setpoint and uses a basic decompression algorithm known as Buhlmann ZHL-16C which has been modified by the use of Gradient Factors.

  • Open Circuit / Closed Circuit w/ Fixed
  • PP02 or External PPO2
  • 2-Button Push OC Bailout
  • Air, Nitrox, Trimix and Heliox
  • Gradient Factors Conservatism
  • User Entered GF
  • Easy to Read
  • Simple to Use
  • Adaptive Menus
  • Large OLED Display
  • Automatic Setpoint Switching
  • Ascent Rate Display
  • Battery Warning
  • Battery Voltage
  • Metric with 1 Decimal Place and Imperial
  • CNS Tracking
  • Automatic Backlight

Complete Customisation

Customize the Hollis Prism 2

A Full Range of Customisation Options

Ordering a Hollis Prism 2 has never been easier with the Rebreathers UK Prism 2 Builder option. Quickly add accessories such as our high performance BOV, tanks and valves, wing and harness type, all right from the factory.

Build Your Prism 2 Rebreather

Full Feature List

  • Front mounted counter lungs for Industry low work of breathing and hydrostatic loading
  • Back mounted counterlungs Improved streamlining with less drag and better horizontal trim. Also features a new upstream valve design.
  • Unit weight Fully charged, in standard configuration - approx. 47lbs
  • 3.5 Liter split counter lungs Inhale and exhale counter lungs for high work loads
  • Counter lung drains Easy to remove water during a dive
  • All gas lines external to the Prevents leaks from affecting breathing loop 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 Manually control oxygen PPO2
  • Bail out valve option High-performance open circuit bailout
  • Integral Harness and BC or Ready to dive out of the box
  • Backplate Standard
  • Full range of wings/harness Ultimate customization
  • Accepts 13, 19, or 30 cu.ft. cylinders Flexible gas management
  • Eye-level LED primary display Easy to monitor system status
  • Displays PPO2 for each oxygen sensor Used to control PPO2 manually, assure electronics system is nominal
  • External power switch Easy to power on
  • Push-Button O2 calibration Easy to calibrate
  • Large OLED secondary display Easy to read, even for your buddy
  • PPO2 monitoring of three sensors Continuous display of each sensor’s PPO2, MV reading easy to access Air, Nitrox, Trimix and Heliox Ready for any dive plan
  • 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 % CNS based on real time oxygen exposure
  • Software update via web Available
  • Bluetooth Dive log download and software updates


Length 21 in (53.3 cm)
Width 17 in (43.2 cm)
Depth 9 in (22.9 cm)
Buoyancy Neutral
Weight Approx. 47 lb with tanks
Scrubber Flow Design Radial
Counterlungs Front Mount 3.5L / Back Mount 4.0L
PO2 Set Points Adjustable (0.7, 1.0, 1.2, 1.3, 1.4)
O2 Sensors 3 Galvanic
Sensor Life 12 months in air or 100 hours dive time
Heads Up Display Yes, 9V battery powered sequential LED
Handset Yes, (Shearwater Petrel) Powered by Lithium Cell
Battery Type 9V Alkaline / 3.6v Lithium Cell
Battery Life 40 Hours
Automatic Setpoint Switch Yes
Integrated Weight System Yes (Optional)
Scrubber Duration EN 14143 testing rated the Prism 2 at 40m 4 Deg C (1.6L/min of Co2) at 190mins/3 hours 10mins on AIR Dil and 215mins/3 hours 35mins on Trimix

Hollis Prism 2 Rebreather

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