Selecting the Show In Drop-Down Lists check box indicates that the item is available for selection on item-related fields.
Once you clear this check box on the Items or Multi-Site Items form and designate the item as not available, the item will not display in a drop-down list on any form. However, you may manually enter a valid item number.
The default value of this check box is selected. You can select or clear this check box at any time.
NOTE: The availability of an item record is specific to a site. If the same item record is used in more than one site, each site will maintain the availability of that record.