I have an EMPI Select TENS Unit which I have had for years. I have been ordering electrodes from ESA and they have worked fine. Suddenly my unit stopped working. I assumed that the wires were no good and I ordered new wires from ESA. Unfortunately the wires were too small and didn't work in my unit. The cost was only $10.00 so I didn't bother sending them back. I ordered the right wires from another company. They cost about $50.00 but the unit still didn't work. It was apparent that the unit itself was defective. I went to the ESA website but they didn't have the EMPI select unit. Accordingly, I found the unit on another company's website and I just ordered it. The cost was another $197.00. The new unit should work and I will continue ordering replacement electrodes from ESA since they have always worked OK.