Product Description: Electronic TENS pulse muscle Stimulator with 6 intensity levels. 2 electrode plates  Operational Heat Therapy (2 heating levels) Built in rechargeable Lithium battery (USB cable charging) Adjustable draw cord with cord lock to fit neck size. Soft fleece cozy cloth, Removable and Washable How to use: 1.Connect the USB cable to the corresponding port on the device. 2.Connect the USB cable to any USB charger, it can be plugged in the portable   power bank, mobile phone battery chargers, laptop and any USB port. 3.Normally it takes 2.53 hours to fully charge the battery. 4.While charging,the indicator light turns on flashing red color, when   full charged,the indicator light will turn to green color. 5.If the battery is full,the device can work continuously for around 3 hours. 6.Machine will be turned off automatically when charging Caution & Warnings: This device will switch off automatically after 15 minutes timer run out. Do not setup or use the massager in a bathroom or similar wet / damp areas. Do not use this device .while driving. Likewise, you should allow your body some rest periods. To avoid straining your muscles too  much, we recommend to not exceed a continuous massage of 15 Minutes