These Oyster Hatchery Grading Rings manufactured by Hydro Composites are designed for Aquaculture and other specialty applications. These rings are fabricated using contact molds built in-house by our skilled staff. Thickness, color, and shape can be altered depending on the application of the sink. If your application requires a size we do not currently manufacture, we can make a mold and produce rings to your specifications. We have the ability to put your concept into CAD to ensure the design meets your satisfaction prior to construction. Hydro Composites manufactures all rings using premium FDA approvable iso-resins, gel coat, and glass materials.