My husband wears them under thin shirts to keep his nipples from showing thru.
Actually, for the upcomming summer, I’d rather what would be left of a T-shirt after you’ve subtracted the A-shirt. When it’s hot, I’d rather not have the extra layer, but I do want the sweat protection (also the nipple hidding quality when used with lighter dress shirts). Maybe I should pair up with a wife-beater and we can buy T-shirts and cut out the A-shirt part for him leaving the rest for me.
Maybe I should market them. The “No Sweat Shirt?”
AGillen: A friend of mine who grew up in Cleveland, Ohio in the 40’s recalls these items as being called “Guinea vests”.