Mastering WooCommerce Products Custom Fields 13

gistfile1.php

add_action( 'woocommerce_product_write_panel_tabs', 'woo_add_custom_admin_product_tab' );

function woo_add_custom_admin_product_tab() {
	?>
	<li class="custom_tab"><a href="#custom_tab_data"><?php _e('My Custom Tab', 'woocommerce'); ?></a></li>
	<?php
}

That's perfect! How would I add fields to this custom tab? I know how to add custom fields to the "general" tab:

add_action('woocommerce_product_options_general_product_data', 'woo_add_custom_general_fields');

But what should I replace woocommerce_product_options_general_product_data with?