A magnetic mounting pad is a magnet that holds objects made of non-ferromagnetic materials, such as plastic car roof signs, to a ferromagnetic material like a car roof.  

Magnetic mounting pads are particularly useful for these tasks due to the amount of shear strength they have.
Shear strength refers to the magnet's ability to resist any forces trying to make the magnet slip from the ferromagnetic surface.

Rubber coating on a threaded stud or through hole magnetic mounting pad, Magnetic mounting pads have a high shear strength due to their rubber coating, Magnetic mounting pads are predominantly used for advertising, as the adverts can be easily changed.

This is because they can securely hold the sign for an extended period of time, but because of the magnetic capabilities, it can be easily removed by the user when they need to.

This is also known as a taxi magnet due to its role of holding taxi signs on the roof of a taxi".
Types of magnetic mounting pad: Threaded stud and through hole magnetic mounting pads, They come in two forms; through hole and threaded stud.