The creation of your own package dimensions is optional except for specific situations. When you create a package dimension, you provide it a name to help you identify it. For more information, see About Automated Box Selection.
Note: The use of Box Size Name is available only in Order Lookup.
Steps
On the Order Lookup tab, under the L, W, and H (Length, Width, and Height) fields, click New.
In the Package Size dialog box, enter:
L, W, and H (Length, Width, and Height) values.
Name (to help you identify the package by name).
Click OK.
Repeat for every possible value that your database would use for a specific box size.