ELECTRODE PAD: High-grade, and biocompatible SEKISUI Japanese gel, which facilitates efficient conducting of the electrical stimulator's current to the patient's skin in a dispersed manner. With spunlace non-woven cloth, it enhances the softness of the electrode and makes it be highly stretchable and flexible. JAPANESE GEL: Japanese Gel is 2 times stickiness of Chinese Gel, and can be used up to 15 times if properly used. 100% SEKISUI Gel is the harmless ingredients and the best fit for even sensitive skin users. UNIVERSAL COMPATIBILITY: 2mm pigtail connectors which is wide compatible with most mainstream TENS units and EMS muscle stimulators. The best replacement accessories for your TENS/EMS device. APPROVAL: FDA(OTC) approved, no prescription needed. Pass SGS biocompatibility test, RoHS and LATEX-FREE test. PRODUCT SET: iStim 2"X2" TENS/EMS Black Electrode Pads 16 Pieces NOTE: DO NOT USE Extra Electrode Gel