If you choose, Amazon will assign units of a single product or ASIN to a single fulfillment center as part of its "Inventory Placement Service."
You only need to deliver your package to the designated fulfillment center; once it arrives, Amazon will separate it and distribute it to several fulfillment centers on your behalf.
When you make a shipment plan, Amazon may distribute units of a single product or ASIN to various Amazon fulfillment centers, which is the default FBA service.
Can I pick the fulfillment facility to which a product is sent?
No. Which fulfillment facility receives a shipment of a product will be decided by Amazon.
Does this service ensure that my package won't be divided up across several fulfillment facilities?
No. Even if a shipment contains numerous items or ASINs, the cargo may still go to different fulfillment centers.
Different fulfillment facilities may receive different unit types of a single product (for example, normal size vs. large).