On the new eBay Interface, please select 4" x 6" PDF as your label format.
On the "Classic" Interface:
1. During the label creation process, please click [Printer and label receipt preferences]
2. On the following pop up, you may pick any of the 4 x 6 label sized printers. For example, you may pick the "Zebra TLP3842 4x6"
3. Click "Save" and continue to purchase your label.