I am currently running Odoo v13 and I am trying to create a field inside the product called (replacement) which takes the values of the Internal Reference (default_code) of any other product. How do I make the field show the Internal Reference only and not the combined name of the product (default_code + name). Also, am I using Many2one correctly or should I change it to another field type. The field is supposedly one2one but there isn't an option for One2one.

Thank you in advance :)