Transcutaneous electrical muscle stimulators; Transcutaneous electrical nerve stimulators; Transcutaneous electrical nerve stimulation electrodes; Transcutaneous electrical nerve stimulation instruments; Medical apparatus for the relief of pain; Medical apparatus and instruments; Medical electrodes; Electrodes for medical purposes; Electrodes for medical use; Apparatus for electrical muscle stimulation; Apparatus for the therapeutic toning of the muscles; Apparatus for the therapeutic stimula...