Thank you for the opportunity to help you with your question!
I would consider combo boxes a feature because they provide an easy and convenient way to fill in information in a database. They are also able to reject any information that is not included in the list. For example, when filling in information in an employee database, combo boxes help in creating more efficiency and are able to reject any job description keyed in that is not in the list of an organization's jobs.
Please let me know if you need any clarification. I'm always happy to answer your questions.