Model
Size
Magento\Usps\Model\Source\Size
What it does
This class provides a source model for USPS package size options in Magento's shipping configuration.
Developers use this when displaying dropdown lists of available USPS package sizes in the admin panel, such as 'Regular', 'Large', or 'Oversize'.
It extends the Generic source class and identifies itself with the 'size' code to retrieve the appropriate configuration values.