The Bentley Fortissimo tennis racquet of 1972 was the first oversize tennis racquet to be produced and demonstrated publicly.[1] Prior to its introduction, all tennis racquets were much smaller in terms of the stringbed size, measured in square inches. Today, that size, known as standard, is not used by any professional player for professional match play.
The Fortissimo was shown in 1972 at the "Spoga", a sporting goods show in Germany. Its designer is Kurt Klemmer, who made the racquet with an epoxy fiberglass process. The Fortissimo was not produced on a commercial scale. Racquet engineer Siegfried Kuebler stated that it did not create a favorable impression with tennis players but was positively received by racquet designers.[2]
The Fortissimo emerged two years prior to the filing of the influential and lucrative patent for racquets sized 95-135 square inches by Prince Sporting Goods (now Prince Sports and commonly called Prince). This resulted in the disqualification of the patent by the German patent authority.[2] The Prince patent was upheld elsewhere and the company became the only highly-successful seller of oversize racquets in their early history. The first was the very flexible aluminum Prince Classic of 1976. Tad Weed introduced the first super-oversize in 1975, to start a line that continues to be sold today.