In early summer 2016, the Postal Service™ plans to establish Priority Mail International® parcel service to Cuba, which already receives Priority Mail International Flat Rate Envelopes and Small Flat Rate Priced Boxes from the Postal Service.
The Priority Mail International parcels to Cuba will be included in country price group 9 and will have a maximum weight of 22 pounds, a maximum length of 59 inches, and a maximum length plus girth of 108 inches. Medium and Large Flat Rate Boxes, with a maximum weight of 20 pounds, will also be available. The parcels will require customs form PS Form 2976-A, Customs Declaration and Dispatch Note CP 72, inside PS Form 2976-E, Customs Declaration Envelope — CP 91 (plastic envelope). No additional merchandise insurance will be available for purchase.
Mailers currently may send Free Matter for the Blind in Priority Mail International Flat Rate Envelopes and Small Flat Rate Priced Boxes. With the addition of Priority Mail International parcel service, mailers will be able to send Free Matter for the Blind in Priority Mail International parcels up to 15 pounds.
We will announce the actual date of implementation in a future Postal Bulletin, and at that time, we will publish revisions to Mailing Standards of the United States Postal Service, International Mail Manual (IMM®).
— Product Classification,
Marketing and Sales, 5-12-16