Great idea, flawed execution
These were a gift for my wife who always has cold feet! There are only 2 sizes, and the ranges are pretty liberal, so it should have come as no surprise when they were too big for her feet. She is around 7.5, and these list the max for small as Women's 8.5, so that extra room does make a difference for her when she's wearing them. I can only imagine someone with a size 5 or 6 foot, they would be swimming in these.<br /><br />That being said, she can wear them and it's noticeable but not a deal-breaker that they are a little too big. The main issue with these warming slippers is that the warming is not consistent throughout the foot. It seems like them heat is mainly concentrated in certain areas like the back heel area. Charging is easy and convenient with an  included USB-C "Y" adapter so you can charge both batteries at once. You have to unzip a pocket on the top of the slippers, pull out the adapter and unplug it. Then reverse after charging. Pretty simple, but it does mean that as you are walking you are bearing the burden of a battery pack on top of each foot. Again, not a deal-breaker, but not ideal. And, as I think others have mentioned, it's real easy to push the buttons on the side of the slippers when you brush up against stuff, it happens all the time to my wife while wearing these.<br /><br />Ultimately, these foot warming slippers do the job, if not perfectly. I've not comparison shopped, but I'm going to opine that the current retail of $80 is high for these. I'd rather pay around $40 now that we have them and have tried them, but again, I don't know what the market is like for these. Recommended, but with some reservations as stated.
Rating: 4 stars