B1 mailing box

You're referring to a B1 Mailing Box!

A B1 Mailing Box is a type of postal box or mailbox that is designed to hold a specific size and weight of mail. In the United States, the B1 Mailing Box is a standard size box that measures 5 inches long, 3.5 inches wide, and 1.5 inches high.

Here are some key characteristics of a B1 Mailing Box:

  1. Size: 5" x 3.5" x 1.5" (12.7 cm x 8.9 cm x 3.8 cm)
  2. Weight: Up to 1 pound (0.45 kg)
  3. Mail classification: First-Class Mail, Priority Mail, and Parcel Post
  4. Dimensions: The box must be at least 5 inches long and 3.5 inches wide to qualify as a B1 Mailing Box.

The B1 Mailing Box is commonly used for sending small packages, such as:

When sending a package in a B1 Mailing Box, you'll need to affix the correct postage and ensure that the package is properly packaged and sealed.

Do you have any specific questions about using a B1 Mailing Box or sending mail in general?