LUXMO&reg; Digital PH Meter and TDS Water Temperature Purity Salinity PPM Pen for Hydroponic Pool Aquarium Fish Tank Water Quality Digital Ph Meter + TDS Tester Aquarium Pool Hydroponic Water Monitor 0-9999 PPM Digital pen style pH meter is an ideal instrument for anywhere you may need to test pH levels Excellent meter, very accurate and durable. Measuring pH Range: 0.0 - 14.0 pH. Resolution: 0.1 pH TDS Range: 0-5000 ppm (mg/L) , Temperature Range: 0-80 C; 32-176 F | Resolution: 1 ppm; Temp. resolution is 0.1 C/F Calibration fluid required but not included