These are the solid brass mirror-finished Hildebrandt blades, highly polished and plated in bright nickel or 24-karat gold.Hildebrandt 4CBC Genuine PremiumBlades, Colorado #4"Copper, 5/PackOffering the best spinner blades on the market, the Hildebrandt Premium Replacement Colorado Blades will improve the performance and action of any spinnerbait to help you catch more fish. Made from a heavy gauge brass base material that is corrosion resistant, the Hildebrandt Premium Replacement Colorado Blades produce a harder thumping vibration than cheap thin blades that usually come standard on most spinnerbait. The Colorado shape is also deeply cupped to enhance vibration, which makes it an ideal choice for low visibility situations like dirty water or night fishing. Completed with a highly polished mirror finish to increase light reflection, the Hildebrandt Premium Replacement Colorado Blades are perfect for breathing new life into old worn out spinnerbaits or creating your own one-of-kind lures.