Coil Spring Assisters are necessary because most standard car springs are designed for comfort of the passengers and are not strong enough for towing and heavy weights carried in the boot.
 
Grayston Coil Spring Assisters and Raisers are manufactured in a hard rubber compound and can be fitted
by the average DIY motorist without special tools.
 
They work by stopping a coil of the spring being compressed.
These should be fitted as a last resort after considering the MAD alternative.

Part No. To Suit Gap Distance
 
GE 13 to suit 18 to 25mm gap
GE 14 to suit 26 to 38mm gap
GE 15 to suit 39 to 51mm gap
GE 15A to suit 51 to 65mm gap

Note:
Gap is determined by the measurement between the coils (daylight) approx halfway down the spring, when the vehicle is jacked up by the body until the wheel is clear off the ground