Dimensions and specifications (each): .5" tall x .5" diameter (+/- .005" tolerance) (12.7mm) Pull force to solid, unpainted, flat steel block: 18 lbs (8.2kg) Poles on flat ends (axially magnetized) Nickel-Copper-Nickel plated Weight .4oz (12g) Surface field 6600 gauss Residual Induction: 14800 gauss (Brmax) Maximum Energy Product: 52MGOe (Bhmax) Maximum safe temperature 165°F (74°C) These are incredibly strong for their size, but can still be handled safely. Never allow children to play with rare earth magnets, they are toxic and mechanically dangerous if swallowed. Pull force does not equal lifting capacity, a number of factors must be considered when calculating a safe lifting capacity for a magnet. As with all neodymium magnets, BE CAREFUL! For your safety and longevity of the magnets, never let them slam together, or impact a hard object, this could cause the magnet to break (neodymium magnets are actually a special ceramic, which is coated with metal so that the ceramic is not exposed to oxygen in the air).