$args = array(

function wptuts_custom_tags() {
add_rewrite_rule("^brand-([^/]+)?",'index.php?post_type=products&brand_name=$matches[1]','top');

flush_rewrite_rules();

function my_post_type_link_filter_function($post_link, $id = 0, $leavename = FALSE) {
if (strpos('%brand_name%', $post_link) === FALSE) {
    $post = &get_post($id);
    $brand_name =get_post_meta($post->ID,'brand',true);

    if(empty($brand_name)){$brand_name = 'default';}
    $post_link = str_replace('%brand_name%',$brand_name, $post_link);

    return $post_link;
}