10 x 13 x 1 1/2 Expandable White Tyvek Envelopes Printed First Class w/ Green Border 100/Case

These envelopes are made from 18 lb. olefin, which makes them ten times stronger than regular paper envelopes. They can expand to hold bulky items easily. And they come with a self - seal closure for your convenience.

These expandable white Tyvek envelopes are super easy to use. First, open the self - seal closure. Then, you can put your bulky items inside as they can expand well. When you're done, just seal the envelope by pressing the self - seal strip firmly. As for maintenance, keep them in a dry place away from sharp objects to avoid tearing. Also, don't expose them to extreme heat or cold as it might affect the material and the self - seal closure.