The Photocell Upgrade allows any Venturi Timed Entryway Foam Sanitizer (24V) to be activated via a photocell sensor and apply foam to the entryway floor, "on-demand", for a set amount of time. The multi-function timer also controls the minimum amount of time between activation, preventing costly over-application when traffic is heavy. Timer settings are field adjustable.  Requires 24VAC electrical input - a locally sourced standard step-down transformer is required.  This upgrade must be specified at the time of purchase.