Pack of 16 individual 2" x 2" Electrode. Sonic Technology is the only factory authorized seller of our branded premium SELF-ADHESIVE and REUSABLE Replacement electrodes. FDA approved over the counter and medical grade, these electrodes are intended for use with most TENS (Transcutaneous Electrical Nerve Stimulator) and Electrical Muscle Stimulators (EMS). Sonic Technology electrode pads incorporate a 2mm female connector, to fit the 2mm male connector usually provided with most MS and TENS unit lead-wires. And with Sonic Technology's Digital NeuroStim TENS and Tonemaster 2200 EMS. Our premium, electrode pads are of excellent quality with a flexible, fabric-backing and superior self-adhesive gel. Each pad measures 50mm by 50mm (approximately 2 in. by 2 in). These self-adhesive pads require no conductive gel. Simply position over the desired muscle group and plug in to your MS or TENS unit. Our premium pads should last for 10 to 30 uses, depending upon care of the pads and condition of the skin. The life of the pads may be extended by cleaning the skin prior to use, cleaning the pads occasionally and storing them according to manufacturer's instructions. For maximum conductivity, it is recommended that one replace the self stick electrodes as soon as the conductive gel begins to wear down. This generally occurs anywhere from 10-30 uses (depending on use and care of the pads). Pad integrity may be increased by keeping electrode pads in their air tight package when not in use, and cleaning the skin prior to placing the pads on the skin. Sonic Technology's branded pads for authenticity and integrity. FDA over the counter and medical grade approval. Since 1981 Sonic Technology guarantees our products. If you have any problems with product defect please contact us for a replacement.