Here is a simple test to perform after you receive your tooling: Place a medium sized ball on a flat surface. Take any one of your MDRS tools and lay it also on the flat surface with the face of the magnet pointing toward the ball. Starting with the magnet about 2 feet away from the ball, slowly move it toward the ball. You do not want the ball to fly toward the magnet, you want to find the point in space when the ball will just start to quiver from the magnetic field. That space between the ball and magnet at the movement points is the effective distance of the magnetic field of the magnet you tested. Keep it that far from computers, credit cards, hearing aids, pace makers, open cans of cork cement, razor blades, and all other magnetic materials to avoid having problems with any MDRS tool.