Probes and electrode pads are disposable components that can be reused for a set amount of time or uses. They must be attached to a toning unit and are not self-powered. Most electrode pads can be reused about 30 times when cared for properly and used against skin that is free of lotions and other oils. Electrode probes have an estimated 3-6 months of consistent use before they should be replaced. These estimates are based on average use and care. Follow handling and storage instructions carefully to get the most of your electrodes.