Multi-select

See Text field for complete documentation.

$box = register_cuztom_meta_box( $id, $post_type, array(
		
    'fields' => array(
        
        array(
            'id'      => '_data_multiselect',
            'type'    => 'multiselect',
            'label'   => 'Field Label',
            'options' => array(
                'value1' => 'Value 1',
                'value2' => 'Value 2',
                'value3' => 'Value 3'
            ),
        ),

        ...
	
    )

) );