Very nice design. You can change grips or use whatever fits your hand and the heating element is inside the bar. Blisters? I hope you were exaggerating. If they really raise blisters (2nd deg. burns) then I'd say they are overkill.The best heated grips come from this company. With 5 heat settings, it gets very warm from the third level onwards, I have never used the fourth or fifth level, as it gives me blisters on my palms.
The website is also available in English, at the top right of the website under DE you will see ENG.
Let's not get too excited about the English version of the website. Only a few words were translated, and the instructions/features remained in German. If I understand the installation correctly, the cylinders get glued (permanently?) inside the handlebar? Some versions are pricey too!