Packages related to the Easypost provider can be found in the Easypost provider setup
You can setup your defaults and specify Length, Width, Height or Weigth.
When enabling the default on a package you can autoinsert a pacakge line in the sales order. (Only if you enable the function in the ShipIT Setuo)
Important to know. If you carrier does not have packages you can insert your package description on the line and click carrier selection.