I bought the foot warmer Beurer FW 20 Cosy with Turbo heating (!!!) and 3-stage circuit. The heating power I think is too low. The following Aufheizwerte I've found in the closed Heizwärmer: (Level 1 about 33 ° C; Stage 2 about 37 ° C; Stage 3 about 41 ° C) When you walk in the foot warmer with your feet, you have until heat setting 3 a feeling of warmth, but this is far too low; the temperature drops again and at first with cold feet you wait long for it, until your feet are reasonably warm.