In the link below, you will find additional document(s) regarding conformity of Hori hardware with EU/UK Regulations.
The documents are offered in .PDF formats for your convenience.
https://hori.jp/info/declarations_of_conformity/
Note: To view the files in .PDF format, you will need Acrobat Reader which can be downloaded for free.
If you wish to save the .PDF file to your computer for later use, right click over the link and choose "Save Link As" or "Save Target As."