add_action( 'pt_cv_item_extra_html', 'cvp_item_extra_html_wofs' );
function cvp_item_extra_html_wofs( $post_id ) {
	$product = wc_get_product( $post_id );
	if ( is_object( $product ) ) {

		// Out of stock
		if ( !$product->is_in_stock() ) {
			echo '<div class="out-of-stock">Out of stock</div>';
		}

		// In Stock
		if ( $product->is_in_stock() ) {
			echo '<div class="in-stock">In stock</div>';
		}

		// On Backorder
		if ( $product->is_on_backorder() ) {
			echo '<div class="on-backorder">On Backorder</div>';
		}

	}
}