Actually, Jandy says that they ARE stainless steel screws:

http://www.zodiacpoolsystems.com/pro...ds/SA5250.ashx

However, there's variations in stainless steel quality, and I'm guessing Jandy's supplier isn't using marine-quality stainless steel....more like cheap stainless steel used on inexpensive stainless steel grills (which rust after just a season or two).