USPS Packaging Instruction 5A

Oxidizing Substances, Organic Peroxides

An oxidizing substance or an organic peroxide that qualifies as a Limited Quantity material within the Postal Service is permitted in the domestic mail for air and surface transportation provided that all applicable requirements in 345 are met.

Proper Shipping Name

ID Number


Required Packaging

Primary Receptacle
Absorbent and Cushioning Material
Secondary Packaging
Outer Packaging

The following labels and text markings must be placed on the address side of the mailpiece unless specified in 221.1 and 325.1.