ZED stands for Z-onal E-mpolyee D-iscount. You buy the ZED pass, the fare you pay is based on mileage "zones".

Below is an example ONLY of ZED fares;

1 1 - 450 $25
2 451 - 750 $29
3 751 - 1600 $36
4 1601 - 3200 $51
5 3201 - 4080 $58
6 4081 - 5000 $66
7 5001 - 6100 $72
8 6101 - 7100 $86
9 7101 - 9999 $97

Any travel in a certain zone cost a fixed amount. So, from 1 mile to 450 miles will cost you 25$ one way. I believe that they are subject to a service charge in some cases, but could be wrong.

I got a ZED fare from LAX to AKL a year and a half ago, the total cost was $215 round trip. I'm sure they have gone up since then.