Chattanooga Cefar TENSMains rechargeable Lithium Polymer battery: Plug your device directly to the mains plug to charge the battery. Fast and complete charge in less than 90 minutes with a battery life of 6 to 10 hours treatment depending on parameters used. 1+1 Function: The Cefar TENS stimulator features 2 independent channels that can be managed separately. Users can select either the same program on both channels, or 2 different programs that can be used