If you need a thin, 5/16" diameter neodymium disc magnet (doesn"t everybody?), the D51 is the magnet for you. Very powerful for it"s size, the D51 is easy magnet to handle. They are a hard to find 5/16" size that have a wide variety of uses. An excellent value.
This size is also available in grade N52 as part number D51-N52