In the middle of the 50s, the Wrist-Rocket Company from Columbus, Nebraska started to produce the Wrist-Rocket. It was the first slingshot with a wristbrace and the surgical tubing with the "chinese handcuff" attachment on the fork ends, like almost all recent manufacturers employ because it is so easy and cost-efficient. The Wrist-Rocket was a success, and it is still available today: It's the Trumark Ws-1! No other slingshot could exist so long, bare the relatively unknown German "Hy-Power".
The inventor of the slingshot, Howard Ellenburg, first sold the slingshot as "Howard's Wrist Locker Slngshot". Later on, Mr. Ellenburg entered into an exclusive distributorship agreement with Saunders, and the slinghsot was sold as "Saunders Wrist Rocket". In 1971, Saunders started to make their own slingshots and from this time on, it was sold as the Trumark Wr-1.
If you want to know more about Trumark's history, visit their webpage.