A standard reason Digital sounder for fireplace, stability and industrial purposes; the Sonos Sounder Beacon is certified to EN54. Dr Zzeus Q&A: If fire alarm indicator products do not meet up with the required criteria, will be the process compliant? This very little issue has mighty items going for it. https://www.firesense.co.uk/type/conventional-fire-system/conventional-sounders-vids-vads/