<?php $img = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'full' ); ?>

<a href="<?php echo $img['0'];?>" class="product_grid <?php if ( has_post_thumbnail() ) { ?>wpex-lightbox<?php } ?>" >
<div class="wpb_column vc_column_container vc_col-sm-4">
    <div class="vc_column-inner">
        <div class="wpb_wrapper bg_img" style="background-image: url('<?php echo $img['0'];?>')">
            <h3><?php the_title(); ?></h3>
            <?php the_content(); ?>
        </div>
    </div>
</div>
</a>