The New York Sets were charter members of World Team Tennis??(WTT) in 1974. Their nickname was an attempt to fit in with the football's Jets, baseball's Mets, and basketball's Nets. In 1976, they acquired superstar Billie Jean King and won the WTT title that year. In 1977 they became the Apples and won another title before folding after the 1978 season.
The sweatshirt is great, but the image on the website needs to be updated. A short sleeved shirt is shown and I think that led to confusion with my initial order.