ALUMINUM SPOOL ADAPTERS

Aluminum handles corrosion pretty well on its own, and that's one of the reasons it gets used in hydraulic fittings and adapters like these. You won't get the rust issues you'd run into with standard steel hardware, so wet or humid environments around the equipment aren't going to eat these things up over time. For long-term use in challenging conditions, the material holds its own without needing coatings or extra treatment.