Your billing always up to date.
In your ChannelDock fulfillment account, you can define box sizes and order options (e.g., thank you card, extra padding, etc.).

When processing an order through ChannelDock WMS or your own WMS, you can specify which box and order options apply.

If you want to print out an invoice summary per customer at the end of the month, all the information you need is right there.
This way you can finish invoicing much faster, without making mistakes.