I want to have a \"select-only\" ComboBox that provides a list of items for the user to select from. Typing should be disabled in the text portion of the
To add a Visual Studio GUI reference, you can find the DropDownStyle options under the Properties of the selected ComboBox:

Which will automatically add the line mentioned in the first answer to the Form.Designer.cs InitializeComponent(), like so:
this.comboBoxBatch.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;