EDI’s permanent portable reference electrode, Model IT, is used to make potential readings in any application where a standard, liquid-junction portable reference electrode is presently being used. The Model IT contains a gel rather than a liquid so it can be used in all positions. The gel provides long maintenance-free service since it does not require refilling or cleaning. Soil contact is through a hardwood plug which offers several advantages over ceramic membranes: it will not clog as readily, it is resistant to salt blockage, and it can be reworked by light sanding or cutting if it becomes contaminated with oil. The Model IT has a twenty year design life and an indefinite shelf life if the end cap is in place. Gelled copper/copper sulfate (CUG) electrodes have a blue housing while gelled silver/silver chloride (AGG) electrodes have a light grey housing. Both models have a 1/4 – 20 threaded stud termination.