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.