12.5″x19″ White Ploy Bubble mailer. Seal-sealing. 50 mailers in a case. Sold by the case. Polyair’s Xpak bubble mailers combine the tear, weather and puncture resistance of a courier envelope with the cushioning of a duraliner bubble lining. Each Xpak mailer is made from 100% polyethylene. Shipping/postage costs for Xpaks is lower than many alternative packages. The white outer surface is ideal for high-quality printing.