No more heat packs. HotRox Hand Warmers can last up to 6 hours in one single charge through your USB charger. 2 temperature settings , 43 degrees and 50 degrees. Portable, Ultra-Light and heats up in 15 seconds. Your best traveling companion to cold weather countries. Elderly People can use the hand warmer on areas where they experience joint pain and rheumatism. Women can place the warmer on their stomach for pain relief.