The 3M Cuno CFSRO TDS MTR is the correct TDS meter for the following filtration systems:
The 3M Cuno - CFSRO TDS Meter is a compatible accessory for the 3M Cuno CFS401200 reverse osmosis water filtration system. This reverse osmosis TDS meter measures the amount of total dissolved solids (TDS) in your water, which can affect taste and clarity. The CFSRO1200 water filter system is capable of reducing up 2,000 ppm (parts per million) of TDS.
3M Cuno - CFSRO TDS Meter specifications: