Dedicated Dual Spring Air-Spring Conversion Kit for WP 43mm Air Forks. The Andreani cartridge allows replacing the original WP air 43 cartridge with a spring system. This "dual spring" system allows a greater feeling on the front and greater smoothness, giving the driver a better sensitivity by facilitating driving and making it less tiring. Built with materials of first choice and anodized to increase its smoothness, the Andreani cartridge is supplied with adapters and springs dedicated to the rider's weight and is designed to be easily replaced with the standard cartridge.