@Scholle , it looks like there is a US vendor who carries these heaters:
CoolRide | Spiegler USA
Also, you say they work perfectly. Few questions though so I can understand better since these look to be the exact approach I am looking for.
How warm do they get through the grips? Toasty or just enough to take the “edge” off?
What range of outdoor temps have you been able to test them to?
How long do they take to heat up?