Superstrong earth magnets. Use in pacifiers
The grade, or "N rating" of the magnet refers to the Maximum Energy Product of the material that the magnet is made from. It refers to the maximum strength that the material can be magnetized to. Generally speaking, the higher the grade, the stronger the magnet. If you need the highest strength in the smallest possible package at room temperature, grade N52 is the strongest available.
N35 - Excellent Cost
N42 - Good Cost / Strength
N52 - Strongest grade available