"The first nuts had consisted of a wedge-shaped piece with an attached cable. Although they were simple in construction, they had a certain weight. Because of this, the problem of retrieving the nut after use quickly arose.

In addition, these early nuts were inert, that is, once inserted into a slot, they remained in place only as long as a pull was exerted on them, otherwise there was a risk of locking them with a lot of force and then not being able to remove them.

These disadvantages have been eliminated by new designs, particularly those defined in U.S. Patent Nos. 4,643,378 and 4,715,568. But these devices are complicated and therefore expensive and deteriorate rapidly.

The purpose of the invention is to present a simple nut, therefore inexpensive, easily recoverable, and with all the safety guarantees."