Custom Fields With Options
Custom Fields of types Drop Down, Radio Buttons, and Checkboxes allow you to set options to choose from.
Here's an example. Let’s add an age level field. Go to the Custom Fields Settings Page.
Make it a drop down field. Save the changes.
The field shows up in the box of additional info under the summary. If the field is a checkbox with multiple options selected, they will be listed in a comma-delimited list.