What are TENS Electrode Pads? 1 pack of four self adhesive 50mm x 50mm (2" x 2") electrode pads for use with TENS machines. Easy to apply & adjust. Lasts around thirty applications, depending on skin condition. Fits most standard TENS machines including Boots. When can I use it? For scientifically proven relief of pain, including: Arthritis Back & Neck Pain Period & Labour pain Repetitive Strain Injury (RSI) Sciatica What size are they? Each pad measures 50mm x 50mm (2" x 2"). How does it work? Just stick on the electrodes & use a TENS machine to reduce your pain. An electrical current is passed through the skin to stimulate nerve endings & produce drug free pain relief. Always follow the manufacturer's operating instructions.