This preamp was developped and is manufactured as part-time business by bassist Francis Deck. He doesn’t sell to outside the US: “Unfortunately, the world still has borders. The HPF-Pre product does not carry a CE marking. There may be other countries where the lack of regulatory approval is also a problem. While I am confident that the HPF-Pre would be approved if tested, the cost of testing runs into the thousands of dollars. This is simply impossible for a very small business.”
However, Francis makes the schematics of his preamps available to public for DIY projects.