The radio facet type
The radio facet type allows your users to filter listings by selecting a single choice among many options. In the example below the options are generated by using the listings types taxonomy.
Parent Term: enter the parent term's ID if you have selected an hierarchical taxonomy as data source.
Sort by: the sorting order of the choices by count, or term order.
Hierarchical: if you've selected an hiearchical taxonomy as data source, this option allows to display indentend child terms.