This is a replacement inline DI tee for your DI resilite. The DI light is not included, this is just the PVC Tee. DI Lights are an economical method of monitoring water quality through resistivity, conductivity, TDS. The bright red or green are easy to read.
Simple Monitoring: the green light indicates the water resistivity is above the threshold value; the red light indicates that it is below. The LED output and solid state circuitry will outlast conventional neon lamps. NOTE: The DI Light monitor requires the water to be flowing in order to operate correctly. The DI Light should not be used as the primary indicator for critical or medical applications.