“What breakers are allowed in this panel” is a perennial topic on many forums.
Here’s the definitive answer: If the panel’s label does NOT mention that specific breaker brand and model, the said breaker is not “legit” for that panel.
The exception are “classified” breakers made by Eaton. They were made and tested by Eaton and classified by UL to fit into almost any panel: http://www.eaton.com/ecm/idcplg?IdcService=GET_FILE&dID=296934
The panel manufacturers may try to IMPLY that they did not authorize those breakers. They cannot win win that argument legally, that’s why they can only IMPLY this – they can’t flat out say that the “Classified” breakers will void their warranty, because that would be against the Magnusson Moss Warranty Act: http://www.connecticut-electric.com/TechDocs/Breakers/UL%20Classification%20Explanation.pdf
I have done a very extensive research on this, so you can take my words to the bank
And no, I do not wok for Eaton