Select Box is one of the generic HTML Form input elements. The snapshot of the form shown below is taken from the CRM application found in default Joget's installation package.
Figure 1: Select Box
Figure 2: Select Box Properties
ID: Element ID
Label: Element Label
Value: Default Value
Size (Rows): Number of rows to show
Multiple Selection: Allow multiple selection
Read Only: Determines if this element is editable
Display Field as Label when Read Only: Display the value of the element as plain text when element is set to be as read only.
Options: Selection options. The options can also be defined using the Options Binder.
Field ID to control available options based on Grouping: To limit the selection options available based on other input field's value.
One may extend the capabilities of this element by adding in Validator as well as mapping the value to a Workflow Variable.
Read more about Validators and Workflow Variables.