Sheer tops--do they really keep you warm?

I’ve seen those sheer tops for sale at Watson’s. The packaging is in Chinese but my mother in law says that it’s supposed to help you keep warm… supposed to be made of silk I guess.

Has anyone tried them? And do they really help you retain body heat?

J.

That’s an odd thing about silk. People say that it keeps you cool in the heat and warm in the cold (as an underlayer). Smart worms.