A package_size refers to a pre-defined set of dimensions and weights for a package. This is designed to allow you to re-use common package sizes when managing shipments without needing to pass the full details of all dimensions and weights with every request.

However, if you provide a package_size_reference value when creating or updating a shipment then the value provided must correspond to an existing pre-configured package size in your account.

  {
  "shipment_contents": [
    {
      "package_size_reference": "my_ref",
      //other shipment_contents properties
    }
  ]
}