Reserving inventory for FBA will ensure that received inventory will not be made available on various channels before they have arrived at Amazon's Fulfillment Center.
Reserving inventory will also increase labor efficiency, because received inventory will be flagged to ensure your shipping department doesn't spend the effort stocking it on the warehouse shelf and then repacking it for your FBA inbound shipment.
Reserve Quantity When Creating a FBA Inbound Shipment
Release Reserves Manually
Auto Reserve Inventory
To automatically reserve quantity every time you create a shipment, enable the client setting Auto Reserve When Adding product to FBA Shipment.
The Inventory Available column can not reflect any changes that occurred after you opened the page. If you want to make sure that you that the quantity you are adding is currently available, enable the client setting Validate Inventory for FBA Shipment. Now, when clicking the Reserve Quantities button, the system will check the actual availability at that moment and will return an error message if there is no availability.
To view the inventory movement after quantity has been reserved, open the "Inventory Movement History" page of the reserved product. The reserved quantity is noted in the grid under the movement type "FBA Reserved."
Mark Qty for Reserve When Creating a Purchase Order