Display child posts of parent (post relations)

Found a solution here https://wordpress.stackexchange.com/questions/60292/wp-query-to-get-child-pages-of-current-page and did a minor tweak!

This code below works just as I wanted!

<?php

$args = array(
    'post_type'      => 'produkt',
    'posts_per_page' => -1,
    'nopaging' => true,
    'post_parent'    => $post->ID,
    'order'          => 'ASC',
    'orderby'        => 'menu_order'
 );

$parent = new WP_Query( $args );
if ( $parent->have_posts() ) : ?>
    <?php while ( $parent->have_posts() ) : $parent->the_post(); ?>
        <div id="parent-<?php the_ID(); ?>" class="parent-page">

           <h1><a href="<?php the_permalink(); ?>"><?php the_post_thumbnail( $_page->ID, 'thumbnail' ); ?></a></h1>
        </div>
    <?php endwhile; ?>
<?php endif; wp_reset_query(); 

?>