HM DIGITAL TDS-EZ Handheld TDS Meter Tester With Large LCD Screen Testing For Hydroponics Gardening Aquariums Reefs Pools Spas Water Treatment Drinking Pure Filter system TDS Measurement Range: 0-9990 ppm Hold and Auto-off function Color:Blue Water Resistant Housing Commercial amd Home Use,Such As Aquariums, Swimming Pools, RO Drinking Water system, Water Filters, Purifiers and More