These early diapers were bulky, heavy products composed of fluff pulp with a rayon topsheet, polyethylene backsheet. In 1966, Pampers launched a 'wingfold' design and by 1969 started a "third size". By this time, Pampers had become a national brand in the United States. Procter and Gamble replaced the pin-on design with tapes in 1971. Toddler and Premature Infant sizes were also introduced. In 1973, P&G developed elasticized single and double gussets around the leg and waist areas to aid in fitting and in containing urine or stool which had not been absorbed. In fact, the first patent for the use of double gussets in a diaper was in 1973 by P&G. In 1982, Pampers introduced an elasticized wingfold diaper with elastic leg gathers and refastenable tapes which was a cross between the early 1960s design and the modern hourglass shape, a feature that was first introduced on Luvs in 1976 and evolved into an industry standard in 1985. In 1986, thin diapers made with absorbent gelling material were released. This made the average weight of a typical medium size diaper decrease by 50%. In 1987, Pampers and Huggies both introduced frontal tape systems which allow repositioning of the lateral tape without tearing the diaper. In the 1990s Pampers introduced a thinner diaper known as Ultra Dry Thins.