For direct measurement of fluids and for potentiometrically determining the endpoint of calcium titrations made with EDTA. Plastic membrane half-cell is unbreakable. Measures calcium from 1.0 to 5 x 10-7 M (40,100 to 0.02 ppm). The sensing element has a gelled PVC membrane. The membrane, ion exchanger and reference solution are fitted in a screw-on replaceable electrode module. Operating temperature range from 0 to 40°C. BNC connector.