About the Specific Costing Method
Specific is a cost flow method that ties the item's cost directly to the location/lot combination where the item received is posted. An item is issued from inventory at the cost tied to the specific location/lot combination.
Because each material transaction must refer to an item/location/lot, the system uses the unit cost for that reference when generating transactions. If you move a purchase receipt or job completion quantity and new unit cost to an existing item/location/lot that already has a non-zero quantity, the system will post the cost change to the Inventory Adjustment account.