Preload spacers lift the vehicle by placing a spacer between the coil and strut top cap. This puts a preload on the coil resulting in the vehicle ride height being raised. WARNING: To install these you much compress the coil spring and remove the top cap. It is best to use a wall-mounted spring compressor to achieve this. Small portable spring compressors can easily slip off the coil spring and cause bodily harm. Always have a professional mechanic perform modification to your vehicle.