function cpt_custom_columns($columns){
    global $post;
    if(isset($_GET['post_type']) && $_GET['post_type'] == "banners"){
        switch($_GET['post_type']){
            case "banners":
                $order = ($_GET['order'] == "ASC") ? "DESC" : "ASC";
                $output = "<a id='sort-banner-order' class='".strtolower($order)."' href='".get_bloginfo('wpurl')."/wp-admin/edit.php?post_type=banners&orderby=meta_value_num&meta_key=order&order=$order'>
                <span>Order</span><span class='sorting-indicator'></span></a>";
                $columns['banner-order'] = $output;
                break;
        }
    }
    return $columns;
}
add_filter('manage_posts_columns', 'cpt_custom_columns');