In the '60s through the early '80s, these were sold in women's magazines. Needless to say, it was a scam for the advertised purpose, although it was probably useful as an exercise / muscle toning device. It was sold by Jack and Eileen Feather, and the ads all featured buxom young women.

Starting in 1965 there were attempts by the post office to shut his business down over materially false claims, which eventually succeeded in 1981 when he was indicted on charges of mail fraud. There was a flurry of back and forth legal activity, and the company finally settled, paying a $1.1M fine and pulling their products from the market in '83. The USPS argued the claims exceeded normal ad puffery, and,

(t)here is substantial evidence that the representations as set out in the attached copy of the advertisement involved in this case are false

Jack and Eileen Feather were also responsible for other health sham products, such as weight loss pants, which I'll post separately.

Here is a photo of the product.