The Postal Service recently unveiled its' new 'additional ounce' Forever stamps after receiving a positive response from customers over the 'Forever Stamp' – a stamp specifically used to mail one ounce First-Class letters anytime in the future despite price changes.

The new stamps will now allow items that weigh more than one ounce, postcards, and bulky or odd-sized envelopes that require hand sorting to be sent at any time.

Designs for the new stamps include the emperor penguin, coastal birds, the Eastern Tiger Swallowtail Butterfly, a vintage tulip, wedding cake, and a stamp in the Literary Arts series that honors writer Flannery O'Connor.

The Forever stamps are classified as 'additional ounce,' 'non-machinable surcharge,' 'two ounce,' and 'three ounce' depending on the usage value.