Hubs

The Shimano HB-M525A hub is ideal for use with 6-bolt disc brake rotors and quick release dropouts. - Double contact sealing - Super polished bearing races for low friction rolling - 6-bolt ISO disc mounting surface

Ratchet freehub bodies have a gloss finish and don't have a seal, as this is fixed on the hub shell. The Ratchet System was the first of this type for DT Swiss; used in the mid-range products like the 350 hubs.