The flash premiums of VADs are between 0.five Hz and a couple of Hz. VADs could include things like a synchronisation perform to reduce the potential of a flash frequency that would result in adverse outcomes, such as inducing epileptic matches, when devices are in near proximity. Dr Zzeus Q&A: https://www.firesense.co.uk/type/conventional-fire-system/conventional-sounders-vids-vads/