Only returning ID. How to get the field values?

Only returning ID. How to get the field values?

I am populating choices for a radio button.

Problem is that it only returns the ID of the row, while I want the actual value for the field (size_groups).
How do I extract this so it list the actuall values, rather than the ID?

My code:
avail_size = f_sizes [ID>0] ;
clear input.f_size;
input.f_size:UI.add(avail_size.size_groups.getall(size_groups));