The combo box component is a list of items which can be selected. The list drops down form a text field after the user presses and arrow button. An element from the list can be selected from the user and then appear in the input text field.
The Combobox enables the user to implement checkboxes on the left of the items in the input text field.
Angular ComboBox with Checkboxes features
One of the useful features of the combo box is binding to XML and JSON.

The combo box allows for multiple elements to be selected.
The dropdown list can be aligned horizontally or vertically. The horizontal alignment can be left or right and the vertical top or bottom.
Keyboard navigation and right to left layout and predefined themes including 3 Angular Material themes are also supported.
You can see an example here.