Bring in opening stock, or re-import to adjust — devices are matched by IMEI, then serial.
CSV or Excel. Columns are matched by name (IMEI, Serial, Product, Capacity, Colour, Grade, Purchase Cost, Selling Price, Status, VAT Status, Location and more), so most refurb-system exports drop straight in. An IMEI or serial is required on each row; everything else is optional. A device already in stock is updated, not duplicated.