The Petrel 3 from Shearwater Research of Canada is a full decompression dive computer incorporating the Bühlmann ZHL-16C algorithm. 
 
Out of the box, all models include open-circuit and closed-circuit Air, Nitrox and Trimix mixed gas functionality.
 
The Petrel 3 includes a richly featured 'gauge mode' configuration, along with a three-axis tilt-compensated digital compass. The included CCR mode for rebreathers provides the ability to perform constant PO2 set point calculations for deco. During a decompression dive, the Petrel 3 provides complete information displays of all required stop times.
 
The Petrel 3 can provide time-to-surface based on "look ahead" at planned gas switches. Multiple gas definition presets are supported with any combination of oxygen, nitrogen and helium. The Petrel 3 will NOT "lockout" after a missed stop or ascent rate violation. The Petrel 3 offers a screen display utilizing a low-power consumption, 320x240 QVGA, full color LCD display. The display will automatically adjust intensity based on available light to make the display easily readable whether on the surface in sunlight, in open water or in a cave.
 
The Perdix 3 is capable of wirelessly connecting to optional SWIFT transmitters giving the diver ability to monitor up to four tank pressures. It is also capable of calculating the Gas Time Remaining (GTR). Air integration is optional for all modes, from OC Rec to CC/BO. The tank pressure(s), in PSI or BAR, and GTR can be displayed to the customizable slots on the main display screen or accessed through the underlying information screens.
 
The Petrel 3 has been designed to accept any type of AA size battery including alkaline, lithium and rechargeable. Included with every Petrel 3 from Dive Gear Express are two elastic straps with buckles, gold contact battery holder and battery already installed (ready to dive out of the box!). The Petrel 3 also includes a titanium bezel and a screen protector already installed to help prevent scratches of the display face.
 
The software includes a complete dive log manager, compatible with both MS Windows and MAC OS X, and can be downloaded from Shearwater's website along with the manual. The dive log manager supports log downloads and firmware updates via the Bluetooth wireless interface of the Petrel.
 
Technical Open-Circuit Features
Air/Nitrox/Trimix capable
5 open-circuit gas switch presets
Bühlmann ZHL-16C algorithm with configurable Gradient Factors
GF presets for sport diving NDL safety factor: High = 35/75, Medium = 40/85, Low = 45/95, plus user defined GF
Optional Varying Permeability Model (VPM-B)
%CNS oxygen exposure tracking
Ascent rate monitor
User configurable haptic (vibration) alerts
Date, time and temp display
Easy to read large full color screen
Easy to use adaptive menus
Logbook of last 1000 hours of diving
Operational to at least { 980 fsw | 300 msw}
Battery voltage and warning
Metric and Imperial
Right or left wrist mountable
Battery life (Saft 3.6V LS14500) up to 100 hours of diving
Battery life (1.5V Alkaline) up to 35 hours of diving
Rebreather Features
Constant PPO2 Set Point
Automatic Set Point Switching
5 additional CCR Diluent gas presets
2 button push OC bailout
Also...
Three-axis tilt-compensated digital compass
Titanium bezel
Wireless Tank Pressure (option transmitter required)
Bluetooth Smart wireless upload/download
User upgradeable firmware
User changeable battery
Dive Log Software
Two Year Limited Warranty