Instruct: Classify a given Amazon review as either positive or negative.
Query: Do not buy!

It worked for about 10 min's at most then one of them never even turned on again (& I used fresh, brand new batteries). The one that 'did' stay on....did not warm my feet at all - they were still freezing cold. I was emabarassed having to pull them out of my shoes while out. Also, the retractable cord is extremely inefficient. I had to pull repeatedly to get the cord back in. Lastly, the retractable cord unit itself is a nuisance around your leg. Now I have to go through the bother of the whole return process. To say I am disappointed is an understatement.