The comm is an advanced piece of technology, used by the Knights of Mata-Nui. It is very similar to that used by the Xal-Fettk. In fact, it was largely based on that, so many of the features are the same.
The Comm uses an internal battery. However, after that runs out, it will run on Solar Energy. It can be charged up using any powers source... Even that used to charge the Chutes with power.
The comm is eqipped with a radio that will reach, roughly, accross Metru-Nui in range. However, its range depends on the power reserves. It also has the ability to enable video radio.
The Comm has a small video panel. This can be used to send video or picture to the other comm. When talking on the comm, the video is turned on and sends video to the other comm and vice versa. To turn this on, however, generally uses more energy that simply using it as a radio.
The comm is equipped with a map. This map will change depending on the island you're on. You can use this to pinpoint places on the map. It will also allow you to send data on your position to other Comms. The map will show fairly important buildings in your vacinity when you use it at the highest zoom level. The Comm is also equipped with GPS, for lack of a better term.
The Comm is equipped with a GPS locator. It can locate the relative vacinity of a target, or yourself should you ever get lost.
In this mode, you can hold the comm up, and it will give you a fairly accurate reading of all the thermal activity in a region of about 15 Bio, slightly more inacurate at 20 Bio, and highly inacurate at 30 Bios distance.