In 1964, Rudi Gernreich succumbed to the Exquisite Form bra company and created the No Bra bra, based somewhat on the success (or notoriety) of his topless bathing suit; it was the 60s, after all, and rebellion over rebellion was also the norm.
The No-Bra was made in small sizes, up to a 34B, and came in three sheer colors: powder puff (a beige-ish pink), black, and white. Here’s a sheer powder puff No Bra.
According to the seller, the tag reads:
Exquisite Form No Bra by Rudi Gernreich 36A Nylon 964
There as also a strapless version called The Band.
Later styles in the Gernreich / Exquisite Form line included the No Back bra and the All In None teddy.