Get order details from $order

$items = $order->get_items();
foreach ( $items as $item ) {
  $product_id = $item['product_id'];
  $product_name = $item['name'];
  $product_variation_id = $item['variation_id'];
  // etc
}

More here:
https://docs.woothemes.com/wc-apidocs/class-WC_Order.html

thanks lorro…