Bikini

This is a 'tan-through' bikini manufactured for Piz-Buin, a Swiss sunscreen manufacturer. It allowed the wearer to acquire a fashionable, 'all-over' suntan through sun-bathing, an activity that reached the height of its popularity in the 1970s.

A Life magazine story from 22 May 1970 reported that Piz Buin had 'developed a specially treated cotton-polyester fabric that let 50% of the tanning ultraviolet rays pass through' the fabric of the bikini. 

This was considered a great convenience: 'Wearing a bikini ... made from the fabric, a sunbather [could] loiter palely on the beach or in the water long enough to brown nicely, and when she is done she is all done (right)' (p. 52).