Insole warmers deliver a great deal of sustained heat, in the low-oxygen environment of a boot. Kept my feet toasty warm during 2 hours of snow shoveling in 10-degree weather. These warmers definitely work better than toe warmers for me.

This product is awesome! It performs better than expected. My favorite brand.

Problem is they are sized for a very small foot. I wear a size 10 boot and these foot warmers covered about half of the inside of my boot-note that the ad does not specify true size.

The box of insole foot warmers expire within six months of receiving. Perhaps this current batch is defective or outdated but they are only lasting three hours tops.