The Laser Printable Permanent Polyester (B-747A) is recommended for alphanumeric and barcode applications and works well on the topside of most circuit boards and IC's. Polyester film with an acrylic pressure-sensitive adhesive and a printable coating formulated especially for laser printers and toners. Shelf life is two years from the date of receipt for this product as long as this product is stored in its original packaging in an environment below 80° F (27° C) and 60% RH.