SET USPS CONTAINERS

[Gho5t]

Where can I set the container to be used by USPS? I only use envelopes.

 

Tried the following:

 

$this->types = array('Express' => 'EXPRESS', 'First Class' => 'First-Class Mail', 'Priority' => 'Priority', 'Parcel' => 'Parcel', 'BPM' => 'Bound Printed Material', 'Library' => 'Library', 'Media' => 'Media Mail');

 

$this->containers = array ( 'Priority' => array('Flat Rate Envelope'));

 

on page \catalog\includes\modules\shipping\usps.php