I have seen this product in use on YouTube. It is called KYT FOR BLACKEN made by Lunda in Czech. I contacted a company who sells it about ordering some & even posted a thread here. Didn't get much interest. It isn't that expensive but you have to use a web browser to translate. The shipping wasn't too bad but would have been cheaper to have multiple bottles shipped to one person in the US then reshipped to individuals. Email conversation went well they are very friendly. https://zbraneliberec.cz/en/weapons-...-oprava-koroze