Neodymium magnets are all graded by the material they are made of. As a very general rule, the higher the grade (the number following the 'N'), the stronger the magnet. The highest grade of neodymium magnet currently available is N52. Any letter following the grade refers to the temperature rating of the magnet.

These small 10x5x2mm Neodymium magnets are N52 grade and extremely strong relative to their size.

This is a great component when dealing with small-scale magnetism and can easily be stacked to form larger magnets with specific shapes.