See Text field for complete documentation.

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

        ...

    )

) );