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add_action( 'woocommerce_single_product_summary', 'mmi_rental_notice', 4 );

   function mmi_rental_notice() {

   	$rentalnotice = '<h3 class="rentalnotice">Rental</h3>';

   	if ( is_product() ) {
   		global $post;
   		$terms = get_the_terms( $post->ID, 'product_cat' );
   		foreach ($terms as $term) {
			if ( 377 === $term->parent ) { //oboe
				echo $rentalnotice;
				break;
			}
            elseif ( 359 === $term->parent ) { //bassoons
            	echo $rentalnotice;
            	break;
            }

   			elseif ( 331 === $term->parent ) { //clarinet
   				echo $rentalnotice;
   				break;
   			}

   			elseif ( 1924 === $term->parent ) { //flute and piccolo
   				echo $rentalnotice;
   				break;
   			}

   			elseif ( 369 === $term->parent ) { //sax
   				echo $rentalnotice;
   				break;
   			}

   			elseif ( 1019 === $term->parent ) { //oboe d amore
   				echo $rentalnotice;
   				break;
   			}

   			elseif ( 355 === $term->parent ) { //english horn rentals
   				echo $rentalnotice;
   				break;
   			}
   		}
   	}

   }