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. Printed “Packing List/Invoice Enclosed.” Large, clear window under printing allows shipping papers to show through and serves as address label. Envelope/Mailer Type: Packing List; Envelope Size: 5 1/2 x 4 1/2; Closure: Self-Adhesive; Flap Type: Square.