For BMW X6 E71 E72 SUV Genuine Kilen Rear Suspension Coil Springs (Pair). We apologise in advance for any inconvenience caused. With Constant Wire Diameter. The suspension spring is an important component within the total suspension system, and contributes significantly to a vehicle’s overall safety and performance. Kilen have over 150 years spring manufacturing experience, and today produce the world’s largest range of coils springs for the automotive aftermarket.