USB Hand Warmer Rapid Double Sided Heating Three Levels Adjustable Rechargeable Digital Hand Warmer for School Space Bear Item Type: USB Hand Warmer Material: Fireproof Material, Silicone, Transparent PC Built in Battery Specification: Li Ion, 5000mAh Start up, heating button: Long press for 2 seconds to start heating. The default level is 45 ℃, and start heating. Continue to short press once to switch to 55 ℃, and start heating. Continue to short press once again to return to 45 ℃ (cycle). digital display the current corresponding temperature level. Under heating status, long press for 2 seconds, and then turn off heating. RGB light key: Short press once to turn on RGB light, start to change different colors circularly, press freeze frame again to keep the current color unchanged, continue to press again to turn off the light. Charging (forward charging): Correctly select the corresponding interface data cable and insert it into the corresponding interface. The heating function does not work under the charging state (if the heating function is inserted under the heating state, the heating function will be forcibly turned off). During the charging process, digital display the real time battery power, the single digit will flash, and the one hundred percent full charge will be on and stop flashing. Charging (reverse charging): Select the corresponding data line, and insert the data line port into the USB socket. The heating function does not work in the reverse charging state (if the heating function is inserted in the charging state, the heating function will be forcibly turned off). During the reverse charging process, digital display the real time battery power. Power display: When the power is off, briefly press the key once to display the current real time power percentage. When the power is lower than Ten percent, the percentage flashes. When the power is 0, it flashes 10 times and then goes out. When the heating is on, the "and" sign lights up and flashes when the power is low. When the power is off, the "and" sign flashes 10 times and then goes out and turns off. When the charging is on, the single digit flashes until one hundred percent of the power is fully charged and stops flashing.one hundred percent