Applied Magnets 1-pc, Grade N42, Strong NdFeB Neodymium Magnet Ring, 4" OD x 3" ID x 1/2". 1 Piece - Made with the Strongest Magnet - Neodymium Magnet. Offers much more holding power than any ceramic magnet. Magnet Grade N42 , stronger than N40, N38 and N35. Magnetized axially through the Thickness 0.5", poles on the flat surfaces. Approximate Pull Force: 130 lbs. Durable Nickel-Cpper-Nickel 3-layer Coated magnet.