Biowrap pain relief pads.2" round non-invasive electrodes with velcro cover.Biowrap pain relief pad placements are different from conventional electrical stimulation.The active electrical field forms beneath and surrounding each pain relief pad.As a result, pain relief pads need to be placed directly over specific locations of pain.Biowave goes beneath the skin surface to block pain receptors.- reusable, velcro-backed, hydrogel electrodes.- electrode placement indicated for maximum effect.- pain relief pads must not touch each other when the unit is turned on.- pain relief pads are reusable but must be tacky to the touch.If not, please use a new set of pain relief pads.