I bought them for summer clothes in case bra straps show but am happy to wear them for color, though hidden, in winter. (joy.lookfab.com)
Open back detail with bra strap style closure to top of key hole. (1stdibs.com)
While not sheer from the front I did notice on visible bra strap on my right shoulder from the back, perhaps because of the way the fabric was sitting. (effortlesslywithroxy.com)