Hidden

See Text field for complete documentation.

PHP

$box = new Cuztom_Meta_Box( $id, $title, $post_type, array(
        
    array(
        'id'            => '_data_hidden',
        'type'          => 'hidden',
        'label'         => 'Field Label',
        'default_value'	=> 'Some value'
    ),

    ...

) );