20mm x 3mm x Hole 3mm N52 Countersunk Ring Rare Earth Neodymium Magnet 20x3mm H3mm

20mm x 3mm (Hole: 3mm, fits #4 / M3) (25/32in x 1/8in (Hole: 1/8in, #4 / M3))
Neodymium Countersunk Disc Magnet – N52 Grade (Pull Force approx. 8.79 lbs).

Key Features:

• Dimensions Metric: 20mm diameter × 3mm thickness with 3mm countersunk hole (90° bevel, fits #4 / M3 screw)
• Dimensions Imperial: 25/32 inch diameter × 1/8 inch thickness with 1/8 inch hole (90° bevel, fits #4 / M3 screw)
• Magnet to steel pull force: approx. 8.79 lbs
• Magnet Grade: N52
• Coating: Triple-Layer Nickel-Copper-Nickel (Ni-Cu-Ni) - Total: 15 – 25 µm
• Material Composition: Neodymium (Nd), Iron (Fe), and Boron (B) – Nd₂Fe₁₄B formula
• Shape: Countersunk Disc
• Magnetization Direction: Axial (Through Thickness)
• Surface Magnetic Field (B₀): ~ -3,693 Gauss
• Hole Diameter: 3 mm (1/8") with 90° countersunk bevel
• Suggested Screw Size: #4 / M3 Flathead Screw (fits 3 mm hole)
• Max Operating Temperature: 80°C (176°F)
• Curie Temperature: 310°C (590°F)
• Residual Induction (Br): 14.3 – 14.8 kGs (1.43 – 1.48 T)
• Max Energy Product ((BH)max): 52.0 MGOe (414 kJ/m³)
• Dimensional Tolerance: ±0.05 mm (±0.002 in)
• Estimated Weight: 6.80 grams (0.240 oz)
• SKU / Part Number: JCN52-CK20-3-H3

Material Description:

Neodymium magnets are made from powerful rare earth metals. These 1/8" thick countersunk discs are ultra-low profile, making them perfect for applications where a strong pull is needed without the bulk. They are the strongest commercially available permanent magnets for their size.

Note: Due to their thin profile, these magnets are brittle. Handle with care to prevent them from snapping together and shattering. Always slide magnets apart rather than lifting.

Mounting & Fastener Recommendation: Features a precision 90° countersunk hole designed to accommodate standard #4 / M3 Flathead Screw (fits 3 mm hole). When mounting to wood, cabinetry, drywall, plastic, or aluminum surfaces, use flathead screws so the head sits flush with the magnet face. Caution: Sintered neodymium is brittle—hand-tighten or use a low clutch setting. Do not overtighten screws directly against the magnet to prevent mechanical cracking.

Warnings and Safety Information:

• Keep away from children. Small magnets pose a choking hazard and can cause serious internal injury if swallowed.
• Avoid contact with pacemakers. Magnetic fields can interfere with medical device operation.
• Handle with caution. Magnets may snap together quickly; keep fingers clear and avoid impact.
• Not a toy. Designed for industrial, professional, and hobbyist use only.
• Thermal Sensitivity. Do not heat above 80°C (176°F) to prevent permanent loss of magnetic strength.