Are you spoilt for choice with our range of 4mm diameter disc magnets? We don't blame you, there is a lot to choose from. 4mm diameter disc magnets, while really small can generate an incredible pull. This makes them particularly popular among model makers including model railway enthusiasts for use in magnetic railway couplings. Because a 4mm diameter x 1.5mm thick neodymium disc magnet can produce a Gauss value of 5600 they are commonly used as therapy magnets for pain relief.