The flash premiums of VADs are between 0.5 Hz and a pair of Hz. VADs may contain a synchronisation perform to remove the potential of a flash frequency that would bring about adverse effects, like inducing epileptic fits, when gadgets are in near proximity. Indicating Services Alignment with Evacuation Processes: https://www.firesense.co.uk/type/conventional-fire-system/conventional-sounders-vids-vads/