Note: USB output voltage:5V/DC The first gear ( red light), The temperature is about 44 The second gear ( white light), The temperature is about 41 The third gear ( blue light), The temperature is about 38 There will be 2-4 of error with different measuring insturments and measuring position!Feature: 1. Package for this heated warm knee support only includes 1 pcs, so we suggest you buy 2pcs at a time to use on both knees. 2. Perfect for relieve muscular aches and joint pains associated with overexertion, strains and sprains as well as pains associated with arthritis, meniscus, osteoarthritis, bursitis, tear etc. 3. Fast-heating electric knee pad: heats in seconds, provides ultra comfy hot therapy for knee arthritis pain relief and injury recovery, keeps knee warm, can also be used on calfs, thighs, arms to relieve muscle soreness and cramps. Supper comfortable for use 4. 1 button control and 3 heat-settings: very easy to operate, you can control the heating temp and time totally by yourself. The power button with LED indicator, it can be operated to red-highest, white-medium, blue-lowest temp setting. Short press the button for once can change to another heat.