For durability and ease of storage, each of the 2"x2" tens unit electrode pads is contained in a resealable plastic bag. Most TENS (Transcutaneous Electrical Nerve Stimulation) devices, EMS massagers, and muscle stimulators are compatible with electrode pads that use a standard 2mm pin connector. Replacement pads for MEDITEK tens units feature a superior adhesive gel, a black carbon conductor, and a white nonwoven backing that make them safe and comfortable to use. It doesn't include latex and won't aggravate your skin. Premium carbon tens machine pads provide exceptionally high conductivity and effective treatment for muscle aches, stiffness, and chronic pain in the elbow, arm, neck, shoulder, wrist, hand, lower and upper back, among other places. These tens units are robust and reusable. In Order For Self-Adhesive Electrodes To Last Longer, Please Be Sure To Follow The Following Advice. Cleanse the skin gently, then pat a towel over it to dry. Press firmly on the skin after placing the electrodes there. After using, place the electrodes on the side of the liner where it says to do so. Replace the sealed bag with the electrodes.