Myron L UltraPen PT1 - Waterproof Conductivity / TDS / Salinity / Temp Pen 

This pen boasts highly stable microprocessor-based circuitry, user-friendly design, and waterproof housing. It delivers you with the best possible combination of useful features, meaningful innovation, and lasting value.

• Measurement range 1 - 9999 µS or ppm (0.0010 - 9.999 ppt salinity)
• Reading accuracy of ±1%
• Calibration point accuracy of ±0.2%. 
• Battery included.