Stretch nylon bikini briefs and bras complemented the adolescent boutique fashions of the 1960s, allowing those to be minimal. DuPont introduced lycra (DuPont's name for spandex) in the same decade. Spandex expanded the range of novelty fabrics available to designers which meant suits could be made to fit like a second skin without heavy linings. "The advent of Lycra allowed more women to wear a bikini," wrote Kelly Killoren Bensimon, a former model and author of "The Bikini Book", "It didn't sag, it didn't bag, and it concealed and revealed. It wasn't so much like lingerie anymore." Increased reliance on stretch fabric led to simplified construction. This fabric allowed designers to create the string bikini, and allowed Rudi Gernreich to create the topless monokini. Alternative swimwear fabrics such as velvet, leather, and crocheted squares surfaced in the early '70s.