I would see them all the time, carried by fashionable young women in Bangkok, who used them to maintain their porcelain-pale complexions. They could be distinguished from umbrellas by their shiny silver top surfaces, but worked to protect from both sun and rain.
I saw them being carried, but never found a vendor. I wasn't looking particularly hard, as I thought it silly to bring one home.
Perhaps I was wrong. I walked a couple of miles in this heat at noontime. I wanted a parasol.