for($i=0; $i<=2; $i++) {
  wp_dropdown_pages( array(
    'id' => $this->field_id.$i,
    'name' => $this->field_name.$i,
    'selected' => (empty($promo_boxes[$i]) ? 0 : $promo_boxes[$i]),
    'post_type' => $this->SELECT_POST_TYPE,
    'show_option_none' => $this->field_label,
  ));
}