A hand warmer is an essential item if you want to keep your palms warm and comfortable during cold weather. Ocoopa Union T2S has four heat levels, and the device can maintain the temperature no matter how cold the climate may be. With a massive 10.000 mAh battery, the warmer is expected to operate for up to 16 hours – enough to keep your hand not freezing throughout the day. The large battery isn’t only being used to generate heat. The device boasts a USB output to recharge a smartphone, headphone, or any small gadget. What’s very interesting is the…