Foot warmer is probably a false name because of heat is hardly something to feel. I want that heat flows from the feet forth through my body, because the feet are cold, everything is cold. Now Since March I have the part and annoyed now again - it's cold and foot warmers only consumes power and is at full power only lukewarm. Of course, the device switches after a while off automatically - which it does not matter whether it is warm or not.
This brand, I'll remember that and nothing more to buy from Beurer. Then I go well but rather in the discounter, because the throw away does not hurt so if it does not work the way you thought it.
Conclusion: Do not buy it, you will only annoy you.