Hi Wclark8,

You can select it if you have sub-assembly items that need to be finished first before the main assembly item. Then, QuickBooks will automatically create them for you along with the main item.

If you like to see some additional references, you can press F1 while you're on the Build Assembly window. This will open the Help window, and you can read the articles about building assemblies.

You can always drop by here if you need anything else.

Have a good day!