Before an order is sent out, make sure the invoice is securely attached. Backed with ultra-tacky adhesive to stick firmly onto most cardboard boxes, ensuring they'll still be there when the shipment arrives. Since the packing list is crucial for inventory management, the envelopes' clear poly construction is designed for easy recognition and quick recovery. Clear Front—Clear window allows shipping papers to show through and serves as address label. Seam Type: Weld; Flap Type: Square; Security Tinted: No; Opening: Open End.