I sell stuff on eBay and Amazon.com all the time, and so these little bubble-wrap envelopes work wonders when mailing out smaller items. From playing cards to writing utensils, these can hold all sorts of things.The only complaint I have is that the bubble-wrap doesn't seem too thick, so sometimes I'm afraid that, when I send more fragile things, USPS will get it broken. But then I just wrap it carefully in a little more bubble-wrap or other kind of protection, and it's fine.I use this one and the size 1 often.