Mailing Standards of the United States Postal Service Domestic Mail Manual > 200 Commercial Letters, Cards, Flats, and Parcels > 280 Commercial MailFirst-Class Package Service —Commercial > 285 Mail Preparation
1.0 Preparation for First-Class Package Service — Commercial
The following standards apply to single-piece First-Class Package Service — Commercial:
To use a permit imprint, the pieces must be of identical weight and, unless all the pieces are in a weight category for which the price does not vary by zone, the pieces must be separated by zone when presented to the Post Office, except under 2.2.
A permit imprint may be used for mailings of nonidentical-weight pieces only if authorized by Business Mailer Support at USPS Headquarters.
Each optional ADC presorted First-Class Package Service — Commercial mailing must meet the applicable standards in 280 and must be labeled as follows: