I buy the Colorado Hairstreak butterfly, nonmachinable surcharge stamps which are currently 99 cents a piece from USPS. They are forever stamps so they will always be good at the price you paid. I put one of those stamps on a #000 bubble mailer and I can mail 1 or 2 chips, never had a problem. The key is I do NOT go inside to the postal counter, I drop it off at the drive up mailbox outside the post office. When you take your letter or package to mail at the counter inside, the first thing that the postal clerk does is dutifully inspect your mail with their little template with the slot and they determine that it is a package. Mail that gets dropped off outside doesn't get inspected. Hope this helps...