The FM-2 Filter Monitor is an innovative device useful to determine when up to 5 filter stages need to be changed. The FM2 monitors the time, and volume of water that has moved through up to 5 filters. Includes a tri-colored indicator light suitable for placement at the base of any non-air gap RO drinking water faucet. The LED indicator disc will illuminate a green, yellow or red light when the water is turned on. The color indicates the percentage of elapsed time and volume used. Auto-Off function conserves battery power. The unit shuts off automatically after 5 minutes of non-use. Uses 2 AA batteries. The timer counts down in months or days (settings can be modified). The volumizer counts up in gallons or liters. Includes an audible alarm (beep). Modern design is perfect for any kitchen. Installs easily.