Keep your workplace or business safe with this Notifier FSP-581 smoke detector. This photoelectric smoke detector is a replacement smoke detector head for a variety of standard bases. It fits with the other control panel series bases made by Notifier. It features a low profile, which allows it to sit close to the ceiling and blend in with your decor. This smoke detector head has a white finish and measures 4.5 inches wide by 4.25 inches long by 2 inches thick.