5-in-1 multifunctional water quality pen, can measure pH, TDS solubility, EC conductivity, salinity and temperature. IP67 waterproof water quality test pen. Replaceable probe, calibration powder bag, three-point automatic calibration. Measurable salinity (sea salt/freshwater salt):Sea salt: Seawater salinity refers to the ratio of total dissolved solids in seawater to the weight of sea salt, usually expressed in grams/kilogram of seawater. (Measuring range: 10.1-200.0ppt);Fresh salt: Fresh water with a salt content of less than 0.5g/L (measuring range: 0.00-25.00%, accuracy: 0.01-5.00%, 5.10-25.00%) Power supply: 3xLR44 batteries Color: As Shown Material: ABS Package Contents: 1 x test pen 3 x calibration bag 1 x English instruction manual Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.