Types of First-Class Mail® - USPS
https://faq.usps.com/articles/Knowledge/Types-of-First-Class-Mail
WEBBasic Pricing for First-Class Mail®. Weight and Size Standards for First-Class Mail®. Types of First-Class Mail®. First-Class Mail® service is the least expensive, most immediate options for mailing postcards, letters, and large envelopes (flats) to retail customers at retail pricing. Commercial pricing, which is discounted from retail ...
DA: 53 PA: 53 MOZ Rank: 16