Electronic muscle stimulators (EMS) have gained traction recently—and for good reason. While the device won't give you toned abs overnight, they can certainly help with muscle building, strengthening, and restoring by sending electric pulses to the muscles that forces them to contract via electrode pads you stick to your skin. Though they're different from Transcutaneous Electrical Nerve Stimulation (TENS) devices—devices meant to alleviate soreness and pain–many muscle stimulators blend dual EMS and TENS capabilities, making them useful for everything from reduced recovery time for athletes to pain relief for those suffering from chronic pain. As a good rule of thumb, the best EMS devices are ones that have various channels, are comfortable to use, and allow you to control the strength of the pulses.