uxcell Digital TDS3 TDS Meter Filter Pen Hold Temp PPM Stick Water Tester Can attach it to your pocket with the clip, also features a black faux leather bag for easy storage and carry. Measurement range of 0-9990ppm and +/-2% highly accurate and quick readings. Data Hold Function: Freeze the measurement to view it out of the water. Auto-off Function; Low power-consumption for years of reliable measurement. Ideal for water TDS testing like aquariums, swimming pools, water filters, and more.