These are maps that you can show on the same page on the same screen.  You have the ability to show anywhere from two to nine maps in the same space and have them advance and rewind all together at the same time.  You can compare different model cycles in the past 24 hours with this feature as well.   When clicking on Poly-Panel under Features menu, you can create your own or also choose some pre-sets made by the SV team.  Base Cycle refers to the benchmark cycle for that poly-panel.  For example, if you want to compare the incoming/current midday 12z cycle against last night’s 0z cycle, the 12z cycle would be the base choice.