Christmas Puppy Polymailers Shipping Supplies Mailing Bags. Unsurpassed Water & Tear Resistance – Superior side seams combined with Heavy Duty polyethylene make these High Quality envelopes highly resistant to water, punctures, and tears Pressure sensitive self seal – Easy packing, tamper-evident, and super secure closure Light Weight & Time Saving – Lower shipping costs combined with faster shipment preparation equal big savings over other packaging option 100% recyclable 10 mailers