It is called Body Glide, I did a google search and found out they sold it at my gym.
It looks like a stick of deoderant.
We used it on our feet, and did not get one single blister. We were wearing new sandals (dumb I know) we didn't have time to properly break them in. I am certain, the Body Glide prevented the blisters.
My husband used it on his legs to prevent chafing.