Hi iluvfish2;
Welcome to the forum.
If you already have the solid aluminum, I would stick with them. If you don't currently have any puck savers, and are looking to purchase them I would purchase the rings. I've only seen the Bisquettes Saver Rings come in uncoated/untreated aluminum, or anodized aluminum. Getting the anodized ones would be preferable. The only difference in performance is that the solid savers are heavier. In theory may cause more wear and tear, but I've had the solid ones for over 12 years with no noticeable effects on the generator.