Folks on the move will appreciate Smart Warmer’s two must-have functions. This hand warmer phone charger does both jobs in a pocket-sized design. Whether you use it for a warm boost during commutes, at sporting events, or as a power bank to recharge your phone, the combined functionality makes this two-in-one problem solver great to keep handy. The 4400 mAh Smart Warmer charges a phone twice or warms your hands for around four to six hours (not both at the same time). The same goes for the 2000 mAh battery, which provides one charge or three to four hours of toasty goodness. Even though you can’t use the charging and warming functions at the same time, the device stays warm for a while after you turn it off, so you still benefit from the heat. It’s a simple (but smart) way to power up—and warm up—in one small device.