The Matrix is one of the variants of the Pelagic hockey puck style computers and is simple and easy to use. It uses a modified Haldanean algorithm with 12 tissue compartments and tracks the last compartment for 24 hours after the last dive, so it works pretty well over multiple dive days.
It will automatically compensate for altitudes up to 14,000 ft and recalibrates to fresh water depth readings at altitudes over 3000 ft.
It will log and display the last 10 dives but is not downloadable.
It has a maximum depth of 250 ft and will accomodate deco stops to 40 ft. If a stop below 40 ft is required, the computer will enter immediate violation mode and will enter gauge mode. It is not really meant for intentional deco diving but will handle a no deco dive gone really wrong scenario very well.
The displays are super simple with red/yellow/green bar graphs for ascent rate and N2 loading and intuitive displays for max depth, times and ceilings.
The Matrix Master is an extended range model (330 ft max depth and deco stops to 60 ft.) with a 12 dive log and download capability. The Matrix Master download kits are really hard to find however and the software works better on a Win 95 or Win 98 system.
Both models use a pair of standard CR2032 lithium watch batteries for power. They are easily replaceable and readily available at your local Wal-mart. You cannot change the battery in the middle of a dive day as it will not save the N2 loading during the change. I dove around a hundred dives per uear with mine and found replacing the battery every 50 dives was a good idea as is installing new batteries before a dive vacation.
I still use a Matrix Master as a backup computer and my spouse and son still use their Matrix computers. The only problem I have had is an inadequate low battery warning on warm days with very cold (below 40 degree) water at depth. On one occasion, the voltage in the weak battery in 80 degree heat was enough to not activate the low battery alarm, but the computer failed at depth when the battery cold soaked.
I have seen a couple pelagic hocky pucks develop some relatively significant (3 to 5 ft) depth errors as they aged but have not seen this occur specifically with a Matrix.
The Matrix and Matrix Master will fit any standard Aqualung / US Divers console and will fit Sherwood and Genesis consoles with the use of a thin plastic adapter ring available from a Sherwood or Genesis dealer. With the adapter they will also fit just about every other console designed for a standard sized depth gauge.
Good computers overall for rec diving as long as you are not planning on nitrox as they are strictly air computers.
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