Features LCD Display                                                          Flex offers a large LCD Display, 24 MASSAGE MODES, and 2 A-B outputs. This unit features a battery life indicator, and built-in lithium battery.	Long Battery Life                                                          NueMedics Flex is a dual-channel battery powered multifunction device. Battery life lasts up to 20 hours!	TENS & PMS                                                          This offers both Transcutaneous Electrical Nerve Stimulator (TENS) and Powered Muscle Simulator (PMS) qualities in one device.