These are high strength Neodymium holding pot magnets in a durable Santoprene rubber coating. The Santoprene rubber coating is to ensure there is protection when positioned on to sensitive surfaces. The rubber coating is also handy for preventing corrosion in aquatic environments. They are durable and easy to use. They can be used to hold or grip things in place or fixing something to a point. They have a pull force ranging from 5kg to 47kg depending on the size of the magnet!