These discs are one of our most popular sizes coated with an epoxy finish. Epoxy is weather resistant, so you can use these magnets outdoors or underwater without risk of corrosion. The epoxy finish will scratch, so these discs aren't recommended for applications where they will be moved frequently.
This size is also available in grade N52 with silver nickel plating as part number
D42-N52, in grade N52 with black nickel plating as part number
D42B-N52, in grade N42 with silver nickel plating as part number
D42, and
diametrically magnetized as part number
D42DIA.