Adding size or UPC stickers to your order is generally a logistical decision for your retailers or picking/packing/shipping department.
From the shipping department’s standpoint, stickers can speed up the picking and size verification before shipping.
From the retailer’s standpoint, size stickers let your customers easily find the size they’re looking for without unfolding a stack of shirts and making a mess.
Universal Product Code… UPC (technically referred to as UPC- consists of 12 numeric digits, that are uniquely assigned to each trade item. Along with the related EAN barcode, the UPC is the barcode mainly used for scanning trade items at the point of sale, per GS specifications.