...'Sexual Armor'!

...designed by Ellen E. Perkins, and filed for a patent to the US Patent Office in early 1908, with the explicit aim of saving young people in particular from the deplorable health hazards, as identified below, of playing with one's ding-a-ling-a-ling. Here's an excerpt from the ingenious inventor's application to the US Patent Office:

ELLEN E. PERKINS, OF BEAVER BAY, MINNESOTA. SEXUAL ARMOR.

No. 875,845.

Specification of Letters Patent. Application filed June 24,1907. Serial No. 380,468,

Patented Jan. 7,1908.

"To all whom it may concern: Be it known that I, Ellen E. Perkins, a citizen of the United States, residing at Beaver Bay, in the county of Lake and State 5 of Minnesota, have invented certain new and useful Improvements in Sexual Armor; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

It is a deplorable but well known fact that one of the most common causes of insanity, imbecility and feeble mindedness, especially in youth, is due to masturbation or self abuse. This is about equally true of both sexes."

(You can read the full text, with misspellings from the OCR conversion process, here.)
And here's the full monty (also via Neatorama):