It is made of three large discs.
The three discs create an area around the city that cuts off channelers from the True Source. The Guardian is similar to a stedding because it stops channelers from embracing the True Source but not destroying their weaves. So a well can be used inside the dome, like when Nynaeve used one to set Aleis Barsalla's crown back on her head with a weave of Air. Men are cut off about a mile around the city and women at the city limits. The third disc creates an even larger area that allows channelers to be tracked. Each of the disks has within it a crystal wedge which ordinarily points to the center of the Guardian's chamber. When a channeler channels, the wedges all swing to point to him or her. When the Guardian detects saidar, the wedges turn red, and when it detects saidin they turn black. The stones around the three rings are marked with highly detailed points of the compass, allowing the channeler's position relative to the ter'angreal to be plotted on a map.