The motherboard has a microprocessor, 916.5 MHz OOK radio, and support circuitry. The power supply board currently sports just a battery connector. The sensor board has a 2 axis Honeywell HMC1002 magnetometer with roughly 1mGauss resolution. All three boards and the lithium battery weigh just under 1 ounce. The basic nodes can be purchased from Crossbow .
Battery life varies depending on what's powered up.
With everything on, the life is just an hour. With the magnetometer off, and the radio turned on only once a second to check for messages, the lifetime is many days. The complete mote and two motes as attractively packaged for dropping . Magnetic materials moving near the magnetometer cause a change in the earth's field, and this change is what the motes detect. The magnetometer signal is sampled at 5 Hz.