We have been working on this for a few years. There are many people that need to stay warm while hunting, boating, skiing, working, or just taking a walk, we designed the Heated Layer to work with the 7.4 volt battery. We had to balance heat, time and weight and i think we did a great job. You wear it as your first layer on your body.
Ordering may seem complicated and may be I should have done this differently.
Choice 1 is the Heated Layer only for those who already have purchased one before and does not need more batteries.
Just select the Size and that is it.
Choice 2 is the Heated Layer for use only on 7.4V.
You select the Heated Layer size, then the battery size. With it comes an extension cable to go from the Heated Layer to the battery, battery charger and a battery belt pouch for the 5.2Amp battery. The 5.2Amp Battery has a built in 4 level controller. The 7.8Amp Battery is bigger, heavier, but will last longer. Competitors will tell you batteries will last 10 hours, but that is frankly a half truth. Sure they will, wink, wink, if you run the heat so low you can't feel anything. Figure 4 hours for the 5.2Amp and 6 hours for the 7.8Amp battery depending on how high you have it set.
7.4V 5.2A Battery with 4 level controller, Belt Pouch, Ext Cable & Euro Plug Charger 27760102
7.4V 5.2A Battery with 4 level controller, Belt Pouch, Ext Cable & World Plugs Charger 27760103
7.4V 7.8A Battery with 4 level controller, Belt Pouch, Ext Cable & World Plugs Charger 27760104
Extra chargers, including a car charger are on: http://www.warmnsafe.com/office-home-use/
If you want extra batteries for this Base Layer, then go to: For another 7.4V 5.4A Battery http://www.warmnsafe.com/battery-7-4volt-5-4amp-with-controller/
For another 7.4V 7.8A Battery http://www.warmnsafe.com/battery-7-4-volt-7-8-amp-with-built-in-controller/
The Heated Layer has 10 areas of heat. The chest, side of the chest, upper arms, neck and lower back.