PAC Racing Beehive Series valve springs combine the latest technologies available to produce the best performing springs on the market. Reducing the top coil of the springs allows for a reduced mass retainer. Additionally, beehive springs offer a multi-arc (ovate or egg-shaped) that allows for the stress distribution of the wire to be equally distributed on the opposing sides of the wire. Combine these features--and the result is a variable-frequency spring that performs at a higher level rpm than traditional springs.