During the early-1960s, the simulated wire wheel covers returned, but with new look designed to emphasize sportiness with their radiating spokes and center "spinner caps." These classic center spinner caps feature a rigidly mounted propeller-like center element, usually with two or three projecting "blades." They were intended to simulate the knock-off hubs that were used on vintage racing vehicles and classic sports cars where a hammer or special wrench was used on the spinner to release or tighten the wheel to the hub.