HQ4100 Portable Multi-Meter with Gel pH Electrode PHC101-1 m Cable Equipped with a single probe input the HQ4100 allows professionals to measure a wide variety of parameters with precision and ease Whether you re testing pH-conductivity-dissolved oxygen-ORP-salinity-TDS-or using ion-selective electrodes-the HQ4100 consistently delivers accurate dependable results for every application Its large full-color display enhances usability by providing clear detailed readings Its IP67-rated rugged design ensures durability and performance for water quality testing anywhere your work takes you Need greater flexibility Consider upgrading to the HQ4200 which features two probe inputs allowing you to monitor more parameters without switching probes Or take it a step further with the HQ4300 offering three probe inputs for simultaneous measurements