Under seat springs

Are the springs that sit under seat available, or is there an alternative that can be used.
What is there purpose anyway to hold down tank?
If that is there purpose then would a rubber doughnut achieve the same outcome?

Hi, suppose you could use rubber? You can't get the springs now that I know of, but Armandos sent me some s1/2 seat springs that you can cut to do the job. Hope this helps....Steve

Cheers for that fella, I've got some s1 seats in loft will drag one down and have a look