On a parabolic the leaves don't sit on top of each other, e.g. there's a cap. This allows each leaf to work independently in a similar manner to a coil spring.
Very clever design really and does work well.
Sadly many/most parabolics sold in the UK are utter ****e

and most of the people who buy them buy the wrong rates so they perform worse than standard springs.
If yours is a 109 hopefully the extra weight will make them work a little better though.