Magnetisation Grade:         N38M
Material: Neodymium-Iron-Boron (NdFeB), Neodymium and Steel 
Magnet ID:              NCD-25105-N38M 
Plating / Coating:  Nickel (Ni-Cu-Ni) / Double Ni / Zinc (Zn) / Epoxy        
Shape:         Disc with Countersunk Hole (countersink hole)   
Countersunk Magnet Size: 
Disc Total Diameter (D):      25 mm
Disc Total Height (H):         10 mm
Small Hole Diameter (d):      5 mm
Tolerance:         ±0.05 mm
Magnetisation Direction:    Axial  /  Radial   
Residual Magnetic Flux Density (Br): 1220-1250 mT (12.2-12.5 kGs)
Energy Density (BH)max:             287-310 KJ/m³  (36-39 MGOe) 
Coercivity Force (Hcb):              ≥ 899 kA/m ( ≥ 11.3 kOe)  
Intrinsic Coercivity Force (Hcj):    ≥ 1114  kA/m ( ≥ 14 kOe)   
Maximum Operation Temperature: 100 °C 
Delivery Time:           14-35 days   

Pot Countersunk magnets are the most efficient design for gripping (other designs are preferable for lifting and attracting across air gaps).
1. Which is the strongest type of magnet?
     Neodymium (more precisely Neodymium-Iron-Boron) Countersunk magnets are the strongest permanent magnets in the world.
2.  Is one pole stronger than the other?
      No, both poles are equally strong.
3. What materials can I use to block/shield magnetic fields?
Magnetic fields cannot be blocked, only redirected. The only materials that will redirect magnetic fields are materials that are ferromagnetic (attracted to magnets), such as iron, steel (which contains iron), cobalt, and nickel. The degree of redirection is proportional to the permeability of the material. The most efficient shielding material is the 80 Nickel family, followed by the 50 Nickel family.