This kit comprises of a comfy supportive foot beds, which can be custom moulded to your foot by the specialist in the shop. Inside the foot bed there is a heating element which sits underneath your toes. A small but powerful battery pack is strapped to the top of your boot, then attaches via a skinny wire to power the element.
The picture above is a great visual to how they work and what a simple yet amazingly effective product this is.
Now this is a pricey investment at €250. I don't regret a penny. This has made my days on the hill a total joy. They manage to keep my toes warm enough so that they don't loose there feeling, and instead of insisting on a cafe break every hour I can ski back country for hours.
The guy in the shop told me that they are designed to keep the ambient temperature in your boots at a comfortable level. For this they do for sure, on setting 1-2 they will last all day long and a constant warm sensation can be felt. Setting 3 I find can be a little too intense, instead I may just use this to warm my toes up initially, then I leave it on setting 1 for the remainder of the day.
The only trouble is I know what heated foot beds in all my shoes.