They have a permanent thermostat. I mounted mine on th ebike and plug in one plug to my liner, works great to 19 degrees!!!
Now they also have battery pack units available.
Chas2007 Blue ABS/NAVI 86,000 smiles and countingTRAXXION Full Monty @ 26,000 miles (worth it if you ever scrape pegs, or ride "sport like")GWRRA, Iron Butt, Wags Pooch trailer, New Hampshire [SIGPIC][/SIGPIC]