Ion-selective electrodes (ISE) translate the activity of a specific ion in solution into a measurable voltage, the same principle as a pH electrode, applied to ammonium, fluoride, chloride, calcium, nitrate, potassium, sodium, lead, sulfide and many others. They are the backbone of water analysis, food safety, soil chemistry, clinical assays, fertilizer QC and environmental monitoring whenever a fast, low-cost alternative to chromatography or atomic spectrometry is needed. ElectroSeek covers nano ISEs (OD 2.5 mm for micro-volume samples), universal half-cell ISEs (OD 12 mm with BNC connector), dual ion kits and dedicated single-ion sensors across more than forty ion-selective electrode products.