The Whitby Hand Warmer is great for any winter activity. Its sleek & compact design allows it to fit easily into any pocket, & in some cases you can slide it into your gloves. The Hand Warmer uses normal lighter fluid to produce more than 10 times the heat as chemical or fuel rod alternative. Whitby say the the hand warmer lasts up to 12 hours on one 0.4oz fill, personally I have had my branded alternative burning for nearly 24 hours. The hand warmer contains wadding that absorbs the lighter fuel so it wont leak out onto you clothes or pocket contents. After filling, replace the burning unit wait a few moments before igniting with a lighter. Dont worry you wont be putting a lit flame into your pocket, the burning unit is platinum-catalyzed glass fiber; this will glow red as it burns the fumes that seep out of the main body of the hand warmer. The burning unit will need replacing from time to time but as far as hand warmers go this one is easy to use & last ages! Great for use on the mountains or any outdoor activity in really cold weather. I use mine to keep my electronics alive as extremely cold weather will sap the charge from your phone, camera or GPS batteries. No Flame The platinum-catalyzed glass reinforced fiber burner offers quick & sure lighting. Produces a radiant heat without the flame. Produces more than 10 times as much heat as most disposable warmers. Economical & constant warmth for up to 24 hours with just 0.4 oz of fuel. Environmentally friendly. Reusable (except for the burner) & virtually pollution free. Low odor Thin profile makes the hand warmer easy to use & carry. Filling jug supplied